diff --git a/configure.ac b/configure.ac
index 373298eb0bcc8..3e68dc71ba26e 100644
--- a/configure.ac
+++ b/configure.ac
@@ -239,12 +239,6 @@ if test "x$use_asm" = xyes; then
   AC_DEFINE(USE_ASM, 1, [Define this symbol to build in assembly routines])
 fi
 
-AC_ARG_WITH([system-univalue],
-  [AS_HELP_STRING([--with-system-univalue],
-  [Build with system UniValue (default is no)])],
-  [system_univalue=$withval],
-  [system_univalue=no]
-)
 AC_ARG_ENABLE([zmq],
   [AS_HELP_STRING([--disable-zmq],
   [disable ZMQ notifications])],
@@ -1506,10 +1500,6 @@ else
   fi
 fi
 
-dnl univalue check
-
-need_bundled_univalue=yes
-
 dnl check if libgmp is present
 AC_CHECK_HEADER([gmp.h],, AC_MSG_ERROR(libgmp headers missing))
 AC_CHECK_LIB([gmp],  [__gmpz_init],GMP_LIBS=-lgmp, AC_MSG_ERROR(libgmp missing))
@@ -1517,50 +1507,6 @@ AC_CHECK_LIB([gmp],  [__gmpz_init],GMP_LIBS=-lgmp, AC_MSG_ERROR(libgmp missing))
 dnl check if immer headers-only library is present
 AC_CHECK_HEADER([immer/map.hpp],, AC_MSG_ERROR(immer map headers missing))
 
-if test x$build_bitcoin_wallet$build_bitcoin_cli$build_bitcoin_tx$build_bitcoind$bitcoin_enable_qt$use_tests$use_bench = xnonononononono; then
-  need_bundled_univalue=no
-else
-
-if test x$system_univalue != xno ; then
-  found_univalue=no
-  if test x$use_pkgconfig = xyes; then
-    : #NOP
-    m4_ifdef(
-      [PKG_CHECK_MODULES],
-      [
-        PKG_CHECK_MODULES([UNIVALUE],[libunivalue >= 1.0.4],[found_univalue=yes],[true])
-      ]
-    )
-  else
-    AC_CHECK_HEADER([univalue.h],[
-      AC_CHECK_LIB([univalue],  [main],[
-        UNIVALUE_LIBS=-lunivalue
-        found_univalue=yes
-      ],[true])
-    ],[true])
-  fi
-
-  if test x$found_univalue = xyes ; then
-    system_univalue=yes
-    need_bundled_univalue=no
-  elif test x$system_univalue = xyes ; then
-    AC_MSG_ERROR([univalue not found])
-  else
-    system_univalue=no
-  fi
-fi
-
-if test x$need_bundled_univalue = xyes ; then
-  UNIVALUE_CFLAGS='-I$(srcdir)/univalue/include'
-  UNIVALUE_LIBS='univalue/libunivalue.la'
-fi
-
-fi
-
-AM_CONDITIONAL([EMBEDDED_UNIVALUE],[test x$need_bundled_univalue = xyes])
-AC_SUBST(UNIVALUE_CFLAGS)
-AC_SUBST(UNIVALUE_LIBS)
-
 AC_MSG_CHECKING([whether to build dashd])
 AM_CONDITIONAL([BUILD_BITCOIND], [test x$build_bitcoind = xyes])
 AC_MSG_RESULT($build_bitcoind)
@@ -1866,10 +1812,6 @@ PKGCONFIG_LIBDIR_TEMP="$PKG_CONFIG_LIBDIR"
 unset PKG_CONFIG_LIBDIR
 PKG_CONFIG_LIBDIR="$PKGCONFIG_LIBDIR_TEMP"
 
-if test x$need_bundled_univalue = xyes; then
-  AC_CONFIG_SUBDIRS([src/univalue])
-fi
-
 ac_configure_args="${ac_configure_args} --disable-shared --with-pic --enable-benchmark=no --enable-module-recovery"
 AC_CONFIG_SUBDIRS([src/secp256k1])
 
diff --git a/src/Makefile.am b/src/Makefile.am
index 40d14a60423b0..1467a26cba534 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -3,7 +3,7 @@
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
-DIST_SUBDIRS = secp256k1 univalue
+DIST_SUBDIRS = secp256k1
 
 AM_LDFLAGS = $(PTHREAD_CFLAGS) $(LIBTOOL_LDFLAGS) $(HARDENED_LDFLAGS) $(GPROF_LDFLAGS) $(SANITIZER_LDFLAGS)
 AM_CXXFLAGS = $(DEBUG_CXXFLAGS) $(HARDENED_CXXFLAGS) $(WARN_CXXFLAGS) $(NOWARN_CXXFLAGS) $(ERROR_CXXFLAGS) $(GPROF_CXXFLAGS) $(SANITIZER_CXXFLAGS)
@@ -31,18 +31,7 @@ BACKTRACE_LIB = -lbacktrace
 endif
 endif #ENABLE_STACKTRACES
 
-if EMBEDDED_UNIVALUE
-LIBUNIVALUE = univalue/libunivalue.la
-
-$(LIBUNIVALUE): $(wildcard univalue/lib/*) $(wildcard univalue/include/*)
-	$(AM_V_at)$(MAKE) $(AM_MAKEFLAGS) -C $(@D) $(@F)
-else
-LIBUNIVALUE = $(UNIVALUE_LIBS)
-endif
-
-BITCOIN_INCLUDES=-I$(builddir) -I$(srcdir)/secp256k1/include $(BDB_CPPFLAGS) $(BOOST_CPPFLAGS) $(LEVELDB_CPPFLAGS)
-
-BITCOIN_INCLUDES += $(UNIVALUE_CFLAGS)
+BITCOIN_INCLUDES=-I$(builddir) -I$(srcdir)/secp256k1/include -I$(srcdir)/$(UNIVALUE_INCLUDE_DIR_INT) $(BDB_CPPFLAGS) $(BOOST_CPPFLAGS) $(LEVELDB_CPPFLAGS)
 
 BLS_LIBS=-lbls-dash -lrelic_s
 
@@ -101,6 +90,7 @@ EXTRA_LIBRARIES += \
   $(LIBBITCOIN_ZMQ)
 
 lib_LTLIBRARIES = $(LIBBITCOINCONSENSUS)
+noinst_LTLIBRARIES =
 
 bin_PROGRAMS =
 noinst_PROGRAMS =
@@ -896,7 +886,6 @@ $(top_srcdir)/$(subdir)/config/dash-config.h.in:  $(am__configure_deps)
 
 clean-local:
 	-$(MAKE) -C secp256k1 clean
-	-$(MAKE) -C univalue clean
 	-rm -f leveldb/*/*.gcda leveldb/*/*.gcno leveldb/helpers/memenv/*.gcda leveldb/helpers/memenv/*.gcno
 	-rm -f config.h
 	-rm -rf test/__pycache__
@@ -942,3 +931,5 @@ endif
 if ENABLE_QT_TESTS
 include Makefile.qttest.include
 endif
+
+include Makefile.univalue.include
diff --git a/src/Makefile.test.include b/src/Makefile.test.include
index 91c736e6e4d35..098bf2d9145cb 100644
--- a/src/Makefile.test.include
+++ b/src/Makefile.test.include
@@ -689,8 +689,26 @@ endif
 	@echo "Running test/util/rpcauth-test.py..."
 	$(PYTHON) $(top_builddir)/test/util/rpcauth-test.py
 	$(AM_V_at)$(MAKE) $(AM_MAKEFLAGS) -C secp256k1 check
-if EMBEDDED_UNIVALUE
-	$(AM_V_at)$(MAKE) $(AM_MAKEFLAGS) -C univalue check
+
+if !ENABLE_FUZZ
+UNIVALUE_TESTS = univalue/test/object univalue/test/unitester univalue/test/no_nul
+noinst_PROGRAMS += $(UNIVALUE_TESTS)
+TESTS += $(UNIVALUE_TESTS)
+
+univalue_test_unitester_SOURCES = $(UNIVALUE_TEST_UNITESTER_INT)
+univalue_test_unitester_LDADD = $(LIBUNIVALUE)
+univalue_test_unitester_CPPFLAGS = -I$(srcdir)/$(UNIVALUE_INCLUDE_DIR_INT) -DJSON_TEST_SRC=\"$(srcdir)/$(UNIVALUE_TEST_DATA_DIR_INT)\"
+univalue_test_unitester_LDFLAGS = -static $(LIBTOOL_APP_LDFLAGS)
+
+univalue_test_no_nul_SOURCES = $(UNIVALUE_TEST_NO_NUL_INT)
+univalue_test_no_nul_LDADD = $(LIBUNIVALUE)
+univalue_test_no_nul_CPPFLAGS = -I$(srcdir)/$(UNIVALUE_INCLUDE_DIR_INT)
+univalue_test_no_nul_LDFLAGS = -static $(LIBTOOL_APP_LDFLAGS)
+
+univalue_test_object_SOURCES = $(UNIVALUE_TEST_OBJECT_INT)
+univalue_test_object_LDADD = $(LIBUNIVALUE)
+univalue_test_object_CPPFLAGS = -I$(srcdir)/$(UNIVALUE_INCLUDE_DIR_INT)
+univalue_test_object_LDFLAGS = -static $(LIBTOOL_APP_LDFLAGS)
 endif
 
 %.cpp.test: %.cpp
diff --git a/src/Makefile.univalue.include b/src/Makefile.univalue.include
new file mode 100644
index 0000000000000..3644e363688de
--- /dev/null
+++ b/src/Makefile.univalue.include
@@ -0,0 +1,6 @@
+include univalue/sources.mk
+
+LIBUNIVALUE = libunivalue.la
+noinst_LTLIBRARIES += $(LIBUNIVALUE)
+libunivalue_la_SOURCES = $(UNIVALUE_LIB_SOURCES_INT) $(UNIVALUE_DIST_HEADERS_INT) $(UNIVALUE_LIB_HEADERS_INT) $(UNIVALUE_TEST_FILES_INT)
+libunivalue_la_CPPFLAGS = $(AM_CPPFLAGS) -I$(srcdir)/$(UNIVALUE_INCLUDE_DIR_INT)
diff --git a/src/masternode/meta.cpp b/src/masternode/meta.cpp
index 2a4df3349ab2f..787ce2ac441f5 100644
--- a/src/masternode/meta.cpp
+++ b/src/masternode/meta.cpp
@@ -6,6 +6,8 @@
 
 #include <timedata.h>
 
+#include <sstream>
+
 CMasternodeMetaMan mmetaman;
 
 const std::string CMasternodeMetaMan::SERIALIZATION_VERSION_STRING = "CMasternodeMetaMan-Version-2";
diff --git a/src/univalue/.cirrus.yml b/src/univalue/.cirrus.yml
new file mode 100644
index 0000000000000..f140fee12bc8c
--- /dev/null
+++ b/src/univalue/.cirrus.yml
@@ -0,0 +1,44 @@
+env:
+  MAKEJOBS: "-j4"
+  RUN_TESTS: "true"
+  BASE_OUTDIR: "$CIRRUS_WORKING_DIR/out_dir_base"
+  DEBIAN_FRONTEND: "noninteractive"
+
+task:
+  container:
+    image: ubuntu:focal
+    cpu: 1
+    memory: 1G
+    greedy: true  # https://medium.com/cirruslabs/introducing-greedy-container-instances-29aad06dc2b4
+
+  matrix:
+    - name: "gcc"
+      env:
+        CC: "gcc"
+        CXX: "g++"
+        APT_PKGS: "gcc"
+    - name: "clang"
+      env:
+        CC: "clang"
+        CXX: "clang++"
+        APT_PKGS: "clang"
+    - name: "mingw"
+      env:
+        CC: ""
+        CXX: ""
+        UNIVALUE_CONFIG: "--host=x86_64-w64-mingw32"
+        APT_PKGS: "g++-mingw-w64-x86-64 gcc-mingw-w64-x86-64 binutils-mingw-w64-x86-64"
+        RUN_TESTS: "false"
+
+  install_script:
+    - apt update
+    - apt install -y pkg-config build-essential libtool autotools-dev automake bsdmainutils
+    - apt install -y $APT_PKGS
+  autogen_script:
+     - ./autogen.sh
+  configure_script:
+     - ./configure --cache-file=config.cache --bindir=$BASE_OUTDIR/bin --libdir=$BASE_OUTDIR/lib $UNIVALUE_CONFIG
+  make_script:
+     - make $MAKEJOBS V=1
+  test_script:
+     - if [ "$RUN_TESTS" = "true" ]; then make $MAKEJOBS distcheck; fi
diff --git a/src/univalue/.travis.yml b/src/univalue/.travis.yml
deleted file mode 100644
index 43a1ed362e7e5..0000000000000
--- a/src/univalue/.travis.yml
+++ /dev/null
@@ -1,51 +0,0 @@
-language: cpp
-
-compiler:
-  - clang
-  - gcc
-
-os:
-  - linux
-  - osx
-
-sudo: false
-
-env:
-  global:
-    - MAKEJOBS=-j3
-    - RUN_TESTS=true
-    - BASE_OUTDIR=$TRAVIS_BUILD_DIR/out
-
-cache:
-  apt: true
-
-addons:
-  apt:
-    packages:
-      - pkg-config
-
-before_script:
-  - if [ -n "$USE_SHELL" ]; then export CONFIG_SHELL="$USE_SHELL"; fi
-  - test -n "$USE_SHELL" && eval '"$USE_SHELL" -c "./autogen.sh"' || ./autogen.sh
-
-script:
-  - if [ -n "$UNIVALUE_CONFIG" ]; then unset CC; unset CXX; fi
-  - OUTDIR=$BASE_OUTDIR/$TRAVIS_PULL_REQUEST/$TRAVIS_JOB_NUMBER-$HOST
-  - UNIVALUE_CONFIG_ALL="--prefix=$TRAVIS_BUILD_DIR/depends/$HOST --bindir=$OUTDIR/bin --libdir=$OUTDIR/lib"
-  - ./configure --cache-file=config.cache $UNIVALUE_CONFIG_ALL $UNIVALUE_CONFIG || ( cat config.log && false)
-  - make -s $MAKEJOBS $GOAL || ( echo "Build failure. Verbose build follows." && make $GOAL ; false )
-  - export LD_LIBRARY_PATH=$TRAVIS_BUILD_DIR/depends/$HOST/lib
-  - if [ "$RUN_TESTS" = "true" ]; then make $MAKEJOBS distcheck; fi
-
-matrix:
-  fast_finish: true
-  include:
-    - os: linux
-      compiler: gcc
-      env: UNIVALUE_CONFIG=--host=x86_64-w64-mingw32 RUN_TESTS=false
-      addons:
-        apt:
-          packages:
-            - g++-mingw-w64-x86-64
-            - gcc-mingw-w64-x86-64
-            - binutils-mingw-w64-x86-64
diff --git a/src/univalue/Makefile.am b/src/univalue/Makefile.am
index 0f5ba599548fa..476f14b922ebf 100644
--- a/src/univalue/Makefile.am
+++ b/src/univalue/Makefile.am
@@ -1,20 +1,17 @@
+include sources.mk
 ACLOCAL_AMFLAGS = -I build-aux/m4
-.PHONY: gen
+.PHONY: gen FORCE
 .INTERMEDIATE: $(GENBIN)
 
-include_HEADERS = include/univalue.h
-noinst_HEADERS = lib/univalue_escapes.h lib/univalue_utffilter.h
+include_HEADERS = $(UNIVALUE_DIST_HEADERS_INT)
+noinst_HEADERS = $(UNIVALUE_LIB_HEADERS_INT)
 
 lib_LTLIBRARIES = libunivalue.la
 
 pkgconfigdir = $(libdir)/pkgconfig
 pkgconfig_DATA = pc/libunivalue.pc
 
-libunivalue_la_SOURCES = \
-	lib/univalue.cpp \
-	lib/univalue_get.cpp \
-	lib/univalue_read.cpp \
-	lib/univalue_write.cpp
+libunivalue_la_SOURCES = $(UNIVALUE_LIB_SOURCES_INT)
 
 libunivalue_la_LDFLAGS = \
 	-version-info $(LIBUNIVALUE_CURRENT):$(LIBUNIVALUE_REVISION):$(LIBUNIVALUE_AGE) \
@@ -30,89 +27,32 @@ $(GENBIN): $(GEN_SRCS)
 	@echo Building $@
 	$(AM_V_at)c++ -I$(top_srcdir)/include -o $@ $<
 
-gen: lib/univalue_escapes.h $(GENBIN)
-	@echo Updating $<
+gen: $(GENBIN) FORCE
+	@echo Updating lib/univalue_escapes.h
 	$(AM_V_at)$(GENBIN) > lib/univalue_escapes.h
 
 noinst_PROGRAMS = $(TESTS) test/test_json
 
-TEST_DATA_DIR=test
-
-test_unitester_SOURCES = test/unitester.cpp
+test_unitester_SOURCES = $(UNIVALUE_TEST_UNITESTER_INT)
 test_unitester_LDADD = libunivalue.la
-test_unitester_CXXFLAGS = -I$(top_srcdir)/include -DJSON_TEST_SRC=\"$(srcdir)/$(TEST_DATA_DIR)\"
+test_unitester_CXXFLAGS = -I$(top_srcdir)/include -DJSON_TEST_SRC=\"$(srcdir)/$(UNIVALUE_TEST_DATA_DIR_INT)\"
 test_unitester_LDFLAGS = -static $(LIBTOOL_APP_LDFLAGS)
 
-test_test_json_SOURCES = test/test_json.cpp
+test_test_json_SOURCES = $(UNIVALUE_TEST_JSON_INT)
 test_test_json_LDADD = libunivalue.la
 test_test_json_CXXFLAGS = -I$(top_srcdir)/include
 test_test_json_LDFLAGS = -static $(LIBTOOL_APP_LDFLAGS)
 
-test_no_nul_SOURCES = test/no_nul.cpp
+test_no_nul_SOURCES = $(UNIVALUE_TEST_NO_NUL_INT)
 test_no_nul_LDADD = libunivalue.la
 test_no_nul_CXXFLAGS = -I$(top_srcdir)/include
 test_no_nul_LDFLAGS = -static $(LIBTOOL_APP_LDFLAGS)
 
-test_object_SOURCES = test/object.cpp
+test_object_SOURCES = $(UNIVALUE_TEST_OBJECT_INT)
 test_object_LDADD = libunivalue.la
 test_object_CXXFLAGS = -I$(top_srcdir)/include
 test_object_LDFLAGS = -static $(LIBTOOL_APP_LDFLAGS)
 
-TEST_FILES = \
-	$(TEST_DATA_DIR)/fail10.json \
-	$(TEST_DATA_DIR)/fail11.json \
-	$(TEST_DATA_DIR)/fail12.json \
-	$(TEST_DATA_DIR)/fail13.json \
-	$(TEST_DATA_DIR)/fail14.json \
-	$(TEST_DATA_DIR)/fail15.json \
-	$(TEST_DATA_DIR)/fail16.json \
-	$(TEST_DATA_DIR)/fail17.json \
-	$(TEST_DATA_DIR)/fail18.json \
-	$(TEST_DATA_DIR)/fail19.json \
-	$(TEST_DATA_DIR)/fail1.json \
-	$(TEST_DATA_DIR)/fail20.json \
-	$(TEST_DATA_DIR)/fail21.json \
-	$(TEST_DATA_DIR)/fail22.json \
-	$(TEST_DATA_DIR)/fail23.json \
-	$(TEST_DATA_DIR)/fail24.json \
-	$(TEST_DATA_DIR)/fail25.json \
-	$(TEST_DATA_DIR)/fail26.json \
-	$(TEST_DATA_DIR)/fail27.json \
-	$(TEST_DATA_DIR)/fail28.json \
-	$(TEST_DATA_DIR)/fail29.json \
-	$(TEST_DATA_DIR)/fail2.json \
-	$(TEST_DATA_DIR)/fail30.json \
-	$(TEST_DATA_DIR)/fail31.json \
-	$(TEST_DATA_DIR)/fail32.json \
-	$(TEST_DATA_DIR)/fail33.json \
-	$(TEST_DATA_DIR)/fail34.json \
-	$(TEST_DATA_DIR)/fail35.json \
-	$(TEST_DATA_DIR)/fail36.json \
-	$(TEST_DATA_DIR)/fail37.json \
-	$(TEST_DATA_DIR)/fail38.json \
-	$(TEST_DATA_DIR)/fail39.json \
-	$(TEST_DATA_DIR)/fail40.json \
-	$(TEST_DATA_DIR)/fail41.json \
-	$(TEST_DATA_DIR)/fail42.json \
-	$(TEST_DATA_DIR)/fail44.json \
-	$(TEST_DATA_DIR)/fail45.json \
-	$(TEST_DATA_DIR)/fail3.json \
-	$(TEST_DATA_DIR)/fail4.json \
-	$(TEST_DATA_DIR)/fail5.json \
-	$(TEST_DATA_DIR)/fail6.json \
-	$(TEST_DATA_DIR)/fail7.json \
-	$(TEST_DATA_DIR)/fail8.json \
-	$(TEST_DATA_DIR)/fail9.json \
-	$(TEST_DATA_DIR)/pass1.json \
-	$(TEST_DATA_DIR)/pass2.json \
-	$(TEST_DATA_DIR)/pass3.json \
-	$(TEST_DATA_DIR)/pass4.json \
-	$(TEST_DATA_DIR)/round1.json \
-	$(TEST_DATA_DIR)/round2.json \
-	$(TEST_DATA_DIR)/round3.json \
-	$(TEST_DATA_DIR)/round4.json \
-	$(TEST_DATA_DIR)/round5.json \
-	$(TEST_DATA_DIR)/round6.json \
-	$(TEST_DATA_DIR)/round7.json
-
-EXTRA_DIST=$(TEST_FILES) $(GEN_SRCS)
+TEST_FILES = $(UNIVALUE_TEST_FILES_INT)
+
+EXTRA_DIST=$(UNIVALUE_TEST_FILES_INT) $(GEN_SRCS)
diff --git a/src/univalue/build-aux/m4/ax_cxx_compile_stdcxx.m4 b/src/univalue/build-aux/m4/ax_cxx_compile_stdcxx.m4
new file mode 100644
index 0000000000000..f7e5137003cfd
--- /dev/null
+++ b/src/univalue/build-aux/m4/ax_cxx_compile_stdcxx.m4
@@ -0,0 +1,962 @@
+# ===========================================================================
+#  https://www.gnu.org/software/autoconf-archive/ax_cxx_compile_stdcxx.html
+# ===========================================================================
+#
+# SYNOPSIS
+#
+#   AX_CXX_COMPILE_STDCXX(VERSION, [ext|noext], [mandatory|optional])
+#
+# DESCRIPTION
+#
+#   Check for baseline language coverage in the compiler for the specified
+#   version of the C++ standard.  If necessary, add switches to CXX and
+#   CXXCPP to enable support.  VERSION may be '11' (for the C++11 standard)
+#   or '14' (for the C++14 standard).
+#
+#   The second argument, if specified, indicates whether you insist on an
+#   extended mode (e.g. -std=gnu++11) or a strict conformance mode (e.g.
+#   -std=c++11).  If neither is specified, you get whatever works, with
+#   preference for no added switch, and then for an extended mode.
+#
+#   The third argument, if specified 'mandatory' or if left unspecified,
+#   indicates that baseline support for the specified C++ standard is
+#   required and that the macro should error out if no mode with that
+#   support is found.  If specified 'optional', then configuration proceeds
+#   regardless, after defining HAVE_CXX${VERSION} if and only if a
+#   supporting mode is found.
+#
+# LICENSE
+#
+#   Copyright (c) 2008 Benjamin Kosnik <bkoz@redhat.com>
+#   Copyright (c) 2012 Zack Weinberg <zackw@panix.com>
+#   Copyright (c) 2013 Roy Stogner <roystgnr@ices.utexas.edu>
+#   Copyright (c) 2014, 2015 Google Inc.; contributed by Alexey Sokolov <sokolov@google.com>
+#   Copyright (c) 2015 Paul Norman <penorman@mac.com>
+#   Copyright (c) 2015 Moritz Klammler <moritz@klammler.eu>
+#   Copyright (c) 2016, 2018 Krzesimir Nowak <qdlacz@gmail.com>
+#   Copyright (c) 2019 Enji Cooper <yaneurabeya@gmail.com>
+#   Copyright (c) 2020 Jason Merrill <jason@redhat.com>
+#
+#   Copying and distribution of this file, with or without modification, are
+#   permitted in any medium without royalty provided the copyright notice
+#   and this notice are preserved.  This file is offered as-is, without any
+#   warranty.
+
+#serial 12
+
+dnl  This macro is based on the code from the AX_CXX_COMPILE_STDCXX_11 macro
+dnl  (serial version number 13).
+
+AC_DEFUN([AX_CXX_COMPILE_STDCXX], [dnl
+  m4_if([$1], [11], [ax_cxx_compile_alternatives="11 0x"],
+        [$1], [14], [ax_cxx_compile_alternatives="14 1y"],
+        [$1], [17], [ax_cxx_compile_alternatives="17 1z"],
+        [m4_fatal([invalid first argument `$1' to AX_CXX_COMPILE_STDCXX])])dnl
+  m4_if([$2], [], [],
+        [$2], [ext], [],
+        [$2], [noext], [],
+        [m4_fatal([invalid second argument `$2' to AX_CXX_COMPILE_STDCXX])])dnl
+  m4_if([$3], [], [ax_cxx_compile_cxx$1_required=true],
+        [$3], [mandatory], [ax_cxx_compile_cxx$1_required=true],
+        [$3], [optional], [ax_cxx_compile_cxx$1_required=false],
+        [m4_fatal([invalid third argument `$3' to AX_CXX_COMPILE_STDCXX])])
+  AC_LANG_PUSH([C++])dnl
+  ac_success=no
+
+  m4_if([$2], [], [dnl
+    AC_CACHE_CHECK(whether $CXX supports C++$1 features by default,
+       ax_cv_cxx_compile_cxx$1,
+      [AC_COMPILE_IFELSE([AC_LANG_SOURCE([_AX_CXX_COMPILE_STDCXX_testbody_$1])],
+        [ax_cv_cxx_compile_cxx$1=yes],
+        [ax_cv_cxx_compile_cxx$1=no])])
+    if test x$ax_cv_cxx_compile_cxx$1 = xyes; then
+      ac_success=yes
+    fi])
+
+  m4_if([$2], [noext], [], [dnl
+  if test x$ac_success = xno; then
+    for alternative in ${ax_cxx_compile_alternatives}; do
+      switch="-std=gnu++${alternative}"
+      cachevar=AS_TR_SH([ax_cv_cxx_compile_cxx$1_$switch])
+      AC_CACHE_CHECK(whether $CXX supports C++$1 features with $switch,
+                     $cachevar,
+        [ac_save_CXX="$CXX"
+         CXX="$CXX $switch"
+         AC_COMPILE_IFELSE([AC_LANG_SOURCE([_AX_CXX_COMPILE_STDCXX_testbody_$1])],
+          [eval $cachevar=yes],
+          [eval $cachevar=no])
+         CXX="$ac_save_CXX"])
+      if eval test x\$$cachevar = xyes; then
+        CXX="$CXX $switch"
+        if test -n "$CXXCPP" ; then
+          CXXCPP="$CXXCPP $switch"
+        fi
+        ac_success=yes
+        break
+      fi
+    done
+  fi])
+
+  m4_if([$2], [ext], [], [dnl
+  if test x$ac_success = xno; then
+    dnl HP's aCC needs +std=c++11 according to:
+    dnl http://h21007.www2.hp.com/portal/download/files/unprot/aCxx/PDF_Release_Notes/769149-001.pdf
+    dnl Cray's crayCC needs "-h std=c++11"
+    for alternative in ${ax_cxx_compile_alternatives}; do
+      for switch in -std=c++${alternative} +std=c++${alternative} "-h std=c++${alternative}"; do
+        cachevar=AS_TR_SH([ax_cv_cxx_compile_cxx$1_$switch])
+        AC_CACHE_CHECK(whether $CXX supports C++$1 features with $switch,
+                       $cachevar,
+          [ac_save_CXX="$CXX"
+           CXX="$CXX $switch"
+           AC_COMPILE_IFELSE([AC_LANG_SOURCE([_AX_CXX_COMPILE_STDCXX_testbody_$1])],
+            [eval $cachevar=yes],
+            [eval $cachevar=no])
+           CXX="$ac_save_CXX"])
+        if eval test x\$$cachevar = xyes; then
+          CXX="$CXX $switch"
+          if test -n "$CXXCPP" ; then
+            CXXCPP="$CXXCPP $switch"
+          fi
+          ac_success=yes
+          break
+        fi
+      done
+      if test x$ac_success = xyes; then
+        break
+      fi
+    done
+  fi])
+  AC_LANG_POP([C++])
+  if test x$ax_cxx_compile_cxx$1_required = xtrue; then
+    if test x$ac_success = xno; then
+      AC_MSG_ERROR([*** A compiler with support for C++$1 language features is required.])
+    fi
+  fi
+  if test x$ac_success = xno; then
+    HAVE_CXX$1=0
+    AC_MSG_NOTICE([No compiler with C++$1 support was found])
+  else
+    HAVE_CXX$1=1
+    AC_DEFINE(HAVE_CXX$1,1,
+              [define if the compiler supports basic C++$1 syntax])
+  fi
+  AC_SUBST(HAVE_CXX$1)
+])
+
+
+dnl  Test body for checking C++11 support
+
+m4_define([_AX_CXX_COMPILE_STDCXX_testbody_11],
+  _AX_CXX_COMPILE_STDCXX_testbody_new_in_11
+)
+
+
+dnl  Test body for checking C++14 support
+
+m4_define([_AX_CXX_COMPILE_STDCXX_testbody_14],
+  _AX_CXX_COMPILE_STDCXX_testbody_new_in_11
+  _AX_CXX_COMPILE_STDCXX_testbody_new_in_14
+)
+
+m4_define([_AX_CXX_COMPILE_STDCXX_testbody_17],
+  _AX_CXX_COMPILE_STDCXX_testbody_new_in_11
+  _AX_CXX_COMPILE_STDCXX_testbody_new_in_14
+  _AX_CXX_COMPILE_STDCXX_testbody_new_in_17
+)
+
+dnl  Tests for new features in C++11
+
+m4_define([_AX_CXX_COMPILE_STDCXX_testbody_new_in_11], [[
+
+// If the compiler admits that it is not ready for C++11, why torture it?
+// Hopefully, this will speed up the test.
+
+#ifndef __cplusplus
+
+#error "This is not a C++ compiler"
+
+#elif __cplusplus < 201103L
+
+#error "This is not a C++11 compiler"
+
+#else
+
+namespace cxx11
+{
+
+  namespace test_static_assert
+  {
+
+    template <typename T>
+    struct check
+    {
+      static_assert(sizeof(int) <= sizeof(T), "not big enough");
+    };
+
+  }
+
+  namespace test_final_override
+  {
+
+    struct Base
+    {
+      virtual ~Base() {}
+      virtual void f() {}
+    };
+
+    struct Derived : public Base
+    {
+      virtual ~Derived() override {}
+      virtual void f() override {}
+    };
+
+  }
+
+  namespace test_double_right_angle_brackets
+  {
+
+    template < typename T >
+    struct check {};
+
+    typedef check<void> single_type;
+    typedef check<check<void>> double_type;
+    typedef check<check<check<void>>> triple_type;
+    typedef check<check<check<check<void>>>> quadruple_type;
+
+  }
+
+  namespace test_decltype
+  {
+
+    int
+    f()
+    {
+      int a = 1;
+      decltype(a) b = 2;
+      return a + b;
+    }
+
+  }
+
+  namespace test_type_deduction
+  {
+
+    template < typename T1, typename T2 >
+    struct is_same
+    {
+      static const bool value = false;
+    };
+
+    template < typename T >
+    struct is_same<T, T>
+    {
+      static const bool value = true;
+    };
+
+    template < typename T1, typename T2 >
+    auto
+    add(T1 a1, T2 a2) -> decltype(a1 + a2)
+    {
+      return a1 + a2;
+    }
+
+    int
+    test(const int c, volatile int v)
+    {
+      static_assert(is_same<int, decltype(0)>::value == true, "");
+      static_assert(is_same<int, decltype(c)>::value == false, "");
+      static_assert(is_same<int, decltype(v)>::value == false, "");
+      auto ac = c;
+      auto av = v;
+      auto sumi = ac + av + 'x';
+      auto sumf = ac + av + 1.0;
+      static_assert(is_same<int, decltype(ac)>::value == true, "");
+      static_assert(is_same<int, decltype(av)>::value == true, "");
+      static_assert(is_same<int, decltype(sumi)>::value == true, "");
+      static_assert(is_same<int, decltype(sumf)>::value == false, "");
+      static_assert(is_same<int, decltype(add(c, v))>::value == true, "");
+      return (sumf > 0.0) ? sumi : add(c, v);
+    }
+
+  }
+
+  namespace test_noexcept
+  {
+
+    int f() { return 0; }
+    int g() noexcept { return 0; }
+
+    static_assert(noexcept(f()) == false, "");
+    static_assert(noexcept(g()) == true, "");
+
+  }
+
+  namespace test_constexpr
+  {
+
+    template < typename CharT >
+    unsigned long constexpr
+    strlen_c_r(const CharT *const s, const unsigned long acc) noexcept
+    {
+      return *s ? strlen_c_r(s + 1, acc + 1) : acc;
+    }
+
+    template < typename CharT >
+    unsigned long constexpr
+    strlen_c(const CharT *const s) noexcept
+    {
+      return strlen_c_r(s, 0UL);
+    }
+
+    static_assert(strlen_c("") == 0UL, "");
+    static_assert(strlen_c("1") == 1UL, "");
+    static_assert(strlen_c("example") == 7UL, "");
+    static_assert(strlen_c("another\0example") == 7UL, "");
+
+  }
+
+  namespace test_rvalue_references
+  {
+
+    template < int N >
+    struct answer
+    {
+      static constexpr int value = N;
+    };
+
+    answer<1> f(int&)       { return answer<1>(); }
+    answer<2> f(const int&) { return answer<2>(); }
+    answer<3> f(int&&)      { return answer<3>(); }
+
+    void
+    test()
+    {
+      int i = 0;
+      const int c = 0;
+      static_assert(decltype(f(i))::value == 1, "");
+      static_assert(decltype(f(c))::value == 2, "");
+      static_assert(decltype(f(0))::value == 3, "");
+    }
+
+  }
+
+  namespace test_uniform_initialization
+  {
+
+    struct test
+    {
+      static const int zero {};
+      static const int one {1};
+    };
+
+    static_assert(test::zero == 0, "");
+    static_assert(test::one == 1, "");
+
+  }
+
+  namespace test_lambdas
+  {
+
+    void
+    test1()
+    {
+      auto lambda1 = [](){};
+      auto lambda2 = lambda1;
+      lambda1();
+      lambda2();
+    }
+
+    int
+    test2()
+    {
+      auto a = [](int i, int j){ return i + j; }(1, 2);
+      auto b = []() -> int { return '0'; }();
+      auto c = [=](){ return a + b; }();
+      auto d = [&](){ return c; }();
+      auto e = [a, &b](int x) mutable {
+        const auto identity = [](int y){ return y; };
+        for (auto i = 0; i < a; ++i)
+          a += b--;
+        return x + identity(a + b);
+      }(0);
+      return a + b + c + d + e;
+    }
+
+    int
+    test3()
+    {
+      const auto nullary = [](){ return 0; };
+      const auto unary = [](int x){ return x; };
+      using nullary_t = decltype(nullary);
+      using unary_t = decltype(unary);
+      const auto higher1st = [](nullary_t f){ return f(); };
+      const auto higher2nd = [unary](nullary_t f1){
+        return [unary, f1](unary_t f2){ return f2(unary(f1())); };
+      };
+      return higher1st(nullary) + higher2nd(nullary)(unary);
+    }
+
+  }
+
+  namespace test_variadic_templates
+  {
+
+    template <int...>
+    struct sum;
+
+    template <int N0, int... N1toN>
+    struct sum<N0, N1toN...>
+    {
+      static constexpr auto value = N0 + sum<N1toN...>::value;
+    };
+
+    template <>
+    struct sum<>
+    {
+      static constexpr auto value = 0;
+    };
+
+    static_assert(sum<>::value == 0, "");
+    static_assert(sum<1>::value == 1, "");
+    static_assert(sum<23>::value == 23, "");
+    static_assert(sum<1, 2>::value == 3, "");
+    static_assert(sum<5, 5, 11>::value == 21, "");
+    static_assert(sum<2, 3, 5, 7, 11, 13>::value == 41, "");
+
+  }
+
+  // http://stackoverflow.com/questions/13728184/template-aliases-and-sfinae
+  // Clang 3.1 fails with headers of libstd++ 4.8.3 when using std::function
+  // because of this.
+  namespace test_template_alias_sfinae
+  {
+
+    struct foo {};
+
+    template<typename T>
+    using member = typename T::member_type;
+
+    template<typename T>
+    void func(...) {}
+
+    template<typename T>
+    void func(member<T>*) {}
+
+    void test();
+
+    void test() { func<foo>(0); }
+
+  }
+
+}  // namespace cxx11
+
+#endif  // __cplusplus >= 201103L
+
+]])
+
+
+dnl  Tests for new features in C++14
+
+m4_define([_AX_CXX_COMPILE_STDCXX_testbody_new_in_14], [[
+
+// If the compiler admits that it is not ready for C++14, why torture it?
+// Hopefully, this will speed up the test.
+
+#ifndef __cplusplus
+
+#error "This is not a C++ compiler"
+
+#elif __cplusplus < 201402L
+
+#error "This is not a C++14 compiler"
+
+#else
+
+namespace cxx14
+{
+
+  namespace test_polymorphic_lambdas
+  {
+
+    int
+    test()
+    {
+      const auto lambda = [](auto&&... args){
+        const auto istiny = [](auto x){
+          return (sizeof(x) == 1UL) ? 1 : 0;
+        };
+        const int aretiny[] = { istiny(args)... };
+        return aretiny[0];
+      };
+      return lambda(1, 1L, 1.0f, '1');
+    }
+
+  }
+
+  namespace test_binary_literals
+  {
+
+    constexpr auto ivii = 0b0000000000101010;
+    static_assert(ivii == 42, "wrong value");
+
+  }
+
+  namespace test_generalized_constexpr
+  {
+
+    template < typename CharT >
+    constexpr unsigned long
+    strlen_c(const CharT *const s) noexcept
+    {
+      auto length = 0UL;
+      for (auto p = s; *p; ++p)
+        ++length;
+      return length;
+    }
+
+    static_assert(strlen_c("") == 0UL, "");
+    static_assert(strlen_c("x") == 1UL, "");
+    static_assert(strlen_c("test") == 4UL, "");
+    static_assert(strlen_c("another\0test") == 7UL, "");
+
+  }
+
+  namespace test_lambda_init_capture
+  {
+
+    int
+    test()
+    {
+      auto x = 0;
+      const auto lambda1 = [a = x](int b){ return a + b; };
+      const auto lambda2 = [a = lambda1(x)](){ return a; };
+      return lambda2();
+    }
+
+  }
+
+  namespace test_digit_separators
+  {
+
+    constexpr auto ten_million = 100'000'000;
+    static_assert(ten_million == 100000000, "");
+
+  }
+
+  namespace test_return_type_deduction
+  {
+
+    auto f(int& x) { return x; }
+    decltype(auto) g(int& x) { return x; }
+
+    template < typename T1, typename T2 >
+    struct is_same
+    {
+      static constexpr auto value = false;
+    };
+
+    template < typename T >
+    struct is_same<T, T>
+    {
+      static constexpr auto value = true;
+    };
+
+    int
+    test()
+    {
+      auto x = 0;
+      static_assert(is_same<int, decltype(f(x))>::value, "");
+      static_assert(is_same<int&, decltype(g(x))>::value, "");
+      return x;
+    }
+
+  }
+
+}  // namespace cxx14
+
+#endif  // __cplusplus >= 201402L
+
+]])
+
+
+dnl  Tests for new features in C++17
+
+m4_define([_AX_CXX_COMPILE_STDCXX_testbody_new_in_17], [[
+
+// If the compiler admits that it is not ready for C++17, why torture it?
+// Hopefully, this will speed up the test.
+
+#ifndef __cplusplus
+
+#error "This is not a C++ compiler"
+
+#elif __cplusplus < 201703L
+
+#error "This is not a C++17 compiler"
+
+#else
+
+#include <initializer_list>
+#include <utility>
+#include <type_traits>
+
+namespace cxx17
+{
+
+  namespace test_constexpr_lambdas
+  {
+
+    constexpr int foo = [](){return 42;}();
+
+  }
+
+  namespace test::nested_namespace::definitions
+  {
+
+  }
+
+  namespace test_fold_expression
+  {
+
+    template<typename... Args>
+    int multiply(Args... args)
+    {
+      return (args * ... * 1);
+    }
+
+    template<typename... Args>
+    bool all(Args... args)
+    {
+      return (args && ...);
+    }
+
+  }
+
+  namespace test_extended_static_assert
+  {
+
+    static_assert (true);
+
+  }
+
+  namespace test_auto_brace_init_list
+  {
+
+    auto foo = {5};
+    auto bar {5};
+
+    static_assert(std::is_same<std::initializer_list<int>, decltype(foo)>::value);
+    static_assert(std::is_same<int, decltype(bar)>::value);
+  }
+
+  namespace test_typename_in_template_template_parameter
+  {
+
+    template<template<typename> typename X> struct D;
+
+  }
+
+  namespace test_fallthrough_nodiscard_maybe_unused_attributes
+  {
+
+    int f1()
+    {
+      return 42;
+    }
+
+    [[nodiscard]] int f2()
+    {
+      [[maybe_unused]] auto unused = f1();
+
+      switch (f1())
+      {
+      case 17:
+        f1();
+        [[fallthrough]];
+      case 42:
+        f1();
+      }
+      return f1();
+    }
+
+  }
+
+  namespace test_extended_aggregate_initialization
+  {
+
+    struct base1
+    {
+      int b1, b2 = 42;
+    };
+
+    struct base2
+    {
+      base2() {
+        b3 = 42;
+      }
+      int b3;
+    };
+
+    struct derived : base1, base2
+    {
+        int d;
+    };
+
+    derived d1 {{1, 2}, {}, 4};  // full initialization
+    derived d2 {{}, {}, 4};      // value-initialized bases
+
+  }
+
+  namespace test_general_range_based_for_loop
+  {
+
+    struct iter
+    {
+      int i;
+
+      int& operator* ()
+      {
+        return i;
+      }
+
+      const int& operator* () const
+      {
+        return i;
+      }
+
+      iter& operator++()
+      {
+        ++i;
+        return *this;
+      }
+    };
+
+    struct sentinel
+    {
+      int i;
+    };
+
+    bool operator== (const iter& i, const sentinel& s)
+    {
+      return i.i == s.i;
+    }
+
+    bool operator!= (const iter& i, const sentinel& s)
+    {
+      return !(i == s);
+    }
+
+    struct range
+    {
+      iter begin() const
+      {
+        return {0};
+      }
+
+      sentinel end() const
+      {
+        return {5};
+      }
+    };
+
+    void f()
+    {
+      range r {};
+
+      for (auto i : r)
+      {
+        [[maybe_unused]] auto v = i;
+      }
+    }
+
+  }
+
+  namespace test_lambda_capture_asterisk_this_by_value
+  {
+
+    struct t
+    {
+      int i;
+      int foo()
+      {
+        return [*this]()
+        {
+          return i;
+        }();
+      }
+    };
+
+  }
+
+  namespace test_enum_class_construction
+  {
+
+    enum class byte : unsigned char
+    {};
+
+    byte foo {42};
+
+  }
+
+  namespace test_constexpr_if
+  {
+
+    template <bool cond>
+    int f ()
+    {
+      if constexpr(cond)
+      {
+        return 13;
+      }
+      else
+      {
+        return 42;
+      }
+    }
+
+  }
+
+  namespace test_selection_statement_with_initializer
+  {
+
+    int f()
+    {
+      return 13;
+    }
+
+    int f2()
+    {
+      if (auto i = f(); i > 0)
+      {
+        return 3;
+      }
+
+      switch (auto i = f(); i + 4)
+      {
+      case 17:
+        return 2;
+
+      default:
+        return 1;
+      }
+    }
+
+  }
+
+  namespace test_template_argument_deduction_for_class_templates
+  {
+
+    template <typename T1, typename T2>
+    struct pair
+    {
+      pair (T1 p1, T2 p2)
+        : m1 {p1},
+          m2 {p2}
+      {}
+
+      T1 m1;
+      T2 m2;
+    };
+
+    void f()
+    {
+      [[maybe_unused]] auto p = pair{13, 42u};
+    }
+
+  }
+
+  namespace test_non_type_auto_template_parameters
+  {
+
+    template <auto n>
+    struct B
+    {};
+
+    B<5> b1;
+    B<'a'> b2;
+
+  }
+
+  namespace test_structured_bindings
+  {
+
+    int arr[2] = { 1, 2 };
+    std::pair<int, int> pr = { 1, 2 };
+
+    auto f1() -> int(&)[2]
+    {
+      return arr;
+    }
+
+    auto f2() -> std::pair<int, int>&
+    {
+      return pr;
+    }
+
+    struct S
+    {
+      int x1 : 2;
+      volatile double y1;
+    };
+
+    S f3()
+    {
+      return {};
+    }
+
+    auto [ x1, y1 ] = f1();
+    auto& [ xr1, yr1 ] = f1();
+    auto [ x2, y2 ] = f2();
+    auto& [ xr2, yr2 ] = f2();
+    const auto [ x3, y3 ] = f3();
+
+  }
+
+  namespace test_exception_spec_type_system
+  {
+
+    struct Good {};
+    struct Bad {};
+
+    void g1() noexcept;
+    void g2();
+
+    template<typename T>
+    Bad
+    f(T*, T*);
+
+    template<typename T1, typename T2>
+    Good
+    f(T1*, T2*);
+
+    static_assert (std::is_same_v<Good, decltype(f(g1, g2))>);
+
+  }
+
+  namespace test_inline_variables
+  {
+
+    template<class T> void f(T)
+    {}
+
+    template<class T> inline T g(T)
+    {
+      return T{};
+    }
+
+    template<> inline void f<>(int)
+    {}
+
+    template<> int g<>(int)
+    {
+      return 5;
+    }
+
+  }
+
+}  // namespace cxx17
+
+#endif  // __cplusplus < 201703L
+
+]])
diff --git a/src/univalue/configure.ac b/src/univalue/configure.ac
index 8298332ac132c..495b25a53d8ef 100644
--- a/src/univalue/configure.ac
+++ b/src/univalue/configure.ac
@@ -1,7 +1,7 @@
 m4_define([libunivalue_major_version], [1])
 m4_define([libunivalue_minor_version], [1])
-m4_define([libunivalue_micro_version], [3])
-m4_define([libunivalue_interface_age], [3])
+m4_define([libunivalue_micro_version], [4])
+m4_define([libunivalue_interface_age], [4])
 # If you need a modifier for the version number. 
 # Normally empty, but can be used to make "fixup" releases.
 m4_define([libunivalue_extraversion], [])
@@ -14,7 +14,7 @@ m4_define([libunivalue_age], [m4_eval(libunivalue_binary_age - libunivalue_inter
 m4_define([libunivalue_version], [libunivalue_major_version().libunivalue_minor_version().libunivalue_micro_version()libunivalue_extraversion()])
 
 
-AC_INIT([univalue], [1.0.3],
+AC_INIT([univalue], [1.0.4],
         [http://github.com/jgarzik/univalue/])
 
 dnl make the compilation flags quiet unless V=1 is used
@@ -45,6 +45,9 @@ AC_SUBST(LIBUNIVALUE_AGE)
 LT_INIT
 LT_LANG([C++])
 
+dnl Require C++11 compiler (no GNU extensions)
+AX_CXX_COMPILE_STDCXX([11], [noext], [mandatory], [nodefault])
+
 case $host in
   *mingw*)
     LIBTOOL_APP_LDFLAGS="$LIBTOOL_APP_LDFLAGS -all-static"
diff --git a/src/univalue/gen/gen.cpp b/src/univalue/gen/gen.cpp
index 85fe20924acef..b8a6c73f4ec49 100644
--- a/src/univalue/gen/gen.cpp
+++ b/src/univalue/gen/gen.cpp
@@ -1,6 +1,6 @@
 // Copyright 2014 BitPay Inc.
 // Distributed under the MIT software license, see the accompanying
-// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+// file COPYING or https://opensource.org/licenses/mit-license.php.
 
 //
 // To re-create univalue_escapes.h:
@@ -45,7 +45,7 @@ static void outputEscape()
 
 	for (unsigned int i = 0; i < 256; i++) {
 		if (escapes[i].empty()) {
-			printf("\tNULL,\n");
+			printf("\tnullptr,\n");
 		} else {
 			printf("\t\"");
 
diff --git a/src/univalue/include/univalue.h b/src/univalue/include/univalue.h
index 048e162f7dfa5..fc5cf402be3ce 100644
--- a/src/univalue/include/univalue.h
+++ b/src/univalue/include/univalue.h
@@ -1,7 +1,7 @@
 // Copyright 2014 BitPay Inc.
 // Copyright 2015 Bitcoin Core Developers
 // Distributed under the MIT software license, see the accompanying
-// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+// file COPYING or https://opensource.org/licenses/mit-license.php.
 
 #ifndef __UNIVALUE_H__
 #define __UNIVALUE_H__
@@ -14,8 +14,6 @@
 #include <map>
 #include <cassert>
 
-#include <sstream>        // .get_int64()
-
 class UniValue {
 public:
     enum VType { VNULL, VOBJ, VARR, VSTR, VNUM, VBOOL, };
diff --git a/src/univalue/lib/univalue.cpp b/src/univalue/lib/univalue.cpp
index 4c9c15d63e338..c4e59fae744b6 100644
--- a/src/univalue/lib/univalue.cpp
+++ b/src/univalue/lib/univalue.cpp
@@ -1,7 +1,7 @@
 // Copyright 2014 BitPay Inc.
 // Copyright 2015 Bitcoin Core Developers
 // Distributed under the MIT software license, see the accompanying
-// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+// file COPYING or https://opensource.org/licenses/mit-license.php.
 
 #include <stdint.h>
 #include <iomanip>
@@ -178,17 +178,19 @@ bool UniValue::findKey(const std::string& key, size_t& retIdx) const
 
 bool UniValue::checkObject(const std::map<std::string,UniValue::VType>& t) const
 {
-    if (typ != VOBJ)
+    if (typ != VOBJ) {
         return false;
+    }
 
-    for (std::map<std::string,UniValue::VType>::const_iterator it = t.begin();
-         it != t.end(); ++it) {
+    for (const auto& object: t) {
         size_t idx = 0;
-        if (!findKey(it->first, idx))
+        if (!findKey(object.first, idx)) {
             return false;
+        }
 
-        if (values.at(idx).getType() != it->second)
+        if (values.at(idx).getType() != object.second) {
             return false;
+        }
     }
 
     return true;
@@ -228,7 +230,7 @@ const char *uvTypeName(UniValue::VType t)
     }
 
     // not reached
-    return NULL;
+    return nullptr;
 }
 
 const UniValue& find_value(const UniValue& obj, const std::string& name)
diff --git a/src/univalue/lib/univalue_escapes.h b/src/univalue/lib/univalue_escapes.h
index 74596aab6d2c9..3f714f8e5bc4d 100644
--- a/src/univalue/lib/univalue_escapes.h
+++ b/src/univalue/lib/univalue_escapes.h
@@ -34,229 +34,229 @@ static const char *escapes[256] = {
 	"\\u001d",
 	"\\u001e",
 	"\\u001f",
-	NULL,
-	NULL,
+	nullptr,
+	nullptr,
 	"\\\"",
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
 	"\\\\",
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
 	"\\u007f",
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
-	NULL,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
 };
 #endif // BITCOIN_UNIVALUE_UNIVALUE_ESCAPES_H
diff --git a/src/univalue/lib/univalue_get.cpp b/src/univalue/lib/univalue_get.cpp
index 0ad61465452ee..5af89a3561c19 100644
--- a/src/univalue/lib/univalue_get.cpp
+++ b/src/univalue/lib/univalue_get.cpp
@@ -1,7 +1,7 @@
 // Copyright 2014 BitPay Inc.
 // Copyright 2015 Bitcoin Core Developers
 // Distributed under the MIT software license, see the accompanying
-// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+// file COPYING or https://opensource.org/licenses/mit-license.php.
 
 #include <stdint.h>
 #include <errno.h>
@@ -11,6 +11,7 @@
 #include <vector>
 #include <limits>
 #include <string>
+#include <sstream>
 
 #include "univalue.h"
 
@@ -31,7 +32,7 @@ bool ParseInt32(const std::string& str, int32_t *out)
 {
     if (!ParsePrechecks(str))
         return false;
-    char *endp = NULL;
+    char *endp = nullptr;
     errno = 0; // strtol will not set errno if valid
     long int n = strtol(str.c_str(), &endp, 10);
     if(out) *out = (int32_t)n;
@@ -47,7 +48,7 @@ bool ParseInt64(const std::string& str, int64_t *out)
 {
     if (!ParsePrechecks(str))
         return false;
-    char *endp = NULL;
+    char *endp = nullptr;
     errno = 0; // strtoll will not set errno if valid
     long long int n = strtoll(str.c_str(), &endp, 10);
     if(out) *out = (int64_t)n;
diff --git a/src/univalue/lib/univalue_read.cpp b/src/univalue/lib/univalue_read.cpp
index 5c6a1acf75d28..be39bfe57a7a7 100644
--- a/src/univalue/lib/univalue_read.cpp
+++ b/src/univalue/lib/univalue_read.cpp
@@ -1,6 +1,6 @@
 // Copyright 2014 BitPay Inc.
 // Distributed under the MIT software license, see the accompanying
-// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+// file COPYING or https://opensource.org/licenses/mit-license.php.
 
 #include <string.h>
 #include <vector>
@@ -227,7 +227,7 @@ enum jtokentype getJsonToken(std::string& tokenVal, unsigned int& consumed,
             }
 
             else {
-                writer.push_back(*raw);
+                writer.push_back(static_cast<unsigned char>(*raw));
                 raw++;
             }
         }
@@ -244,7 +244,7 @@ enum jtokentype getJsonToken(std::string& tokenVal, unsigned int& consumed,
     }
 }
 
-enum expect_bits {
+enum expect_bits : unsigned {
     EXP_OBJ_NAME = (1U << 0),
     EXP_COLON = (1U << 1),
     EXP_ARR_VALUE = (1U << 2),
diff --git a/src/univalue/lib/univalue_utffilter.h b/src/univalue/lib/univalue_utffilter.h
index a1dd4e0a19d65..95b97b29b7563 100644
--- a/src/univalue/lib/univalue_utffilter.h
+++ b/src/univalue/lib/univalue_utffilter.h
@@ -1,6 +1,6 @@
 // Copyright 2016 Wladimir J. van der Laan
 // Distributed under the MIT software license, see the accompanying
-// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+// file COPYING or https://opensource.org/licenses/mit-license.php.
 #ifndef UNIVALUE_UTFFILTER_H
 #define UNIVALUE_UTFFILTER_H
 
diff --git a/src/univalue/lib/univalue_write.cpp b/src/univalue/lib/univalue_write.cpp
index 827eb9b27154b..3a2c580c7f692 100644
--- a/src/univalue/lib/univalue_write.cpp
+++ b/src/univalue/lib/univalue_write.cpp
@@ -1,9 +1,8 @@
 // Copyright 2014 BitPay Inc.
 // Distributed under the MIT software license, see the accompanying
-// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+// file COPYING or https://opensource.org/licenses/mit-license.php.
 
 #include <iomanip>
-#include <sstream>
 #include <stdio.h>
 #include "univalue.h"
 #include "univalue_escapes.h"
@@ -14,13 +13,13 @@ static std::string json_escape(const std::string& inS)
     outS.reserve(inS.size() * 2);
 
     for (unsigned int i = 0; i < inS.size(); i++) {
-        unsigned char ch = inS[i];
+        unsigned char ch = static_cast<unsigned char>(inS[i]);
         const char *escStr = escapes[ch];
 
         if (escStr)
             outS += escStr;
         else
-            outS += ch;
+            outS += static_cast<char>(ch);
     }
 
     return outS;
diff --git a/src/univalue/sources.mk b/src/univalue/sources.mk
new file mode 100644
index 0000000000000..efab6d277f93a
--- /dev/null
+++ b/src/univalue/sources.mk
@@ -0,0 +1,95 @@
+# - All variables are namespaced with UNIVALUE_ to avoid colliding with
+#     downstream makefiles.
+# - All Variables ending in _HEADERS or _SOURCES confuse automake, so the
+#     _INT postfix is applied.
+# - Convenience variables, for example a UNIVALUE_TEST_DIR should not be used
+#     as they interfere with automatic dependency generation
+# - The %reldir% is the relative path from the Makefile.am. This allows
+#   downstreams to use these variables without having to manually account for
+#   the path change.
+
+UNIVALUE_INCLUDE_DIR_INT = %reldir%/include
+
+UNIVALUE_DIST_HEADERS_INT =
+UNIVALUE_DIST_HEADERS_INT += %reldir%/include/univalue.h
+
+UNIVALUE_LIB_HEADERS_INT =
+UNIVALUE_LIB_HEADERS_INT += %reldir%/lib/univalue_utffilter.h
+UNIVALUE_LIB_HEADERS_INT += %reldir%/lib/univalue_escapes.h
+
+UNIVALUE_LIB_SOURCES_INT =
+UNIVALUE_LIB_SOURCES_INT += %reldir%/lib/univalue.cpp
+UNIVALUE_LIB_SOURCES_INT += %reldir%/lib/univalue_get.cpp
+UNIVALUE_LIB_SOURCES_INT += %reldir%/lib/univalue_read.cpp
+UNIVALUE_LIB_SOURCES_INT += %reldir%/lib/univalue_write.cpp
+
+UNIVALUE_TEST_DATA_DIR_INT = %reldir%/test
+
+UNIVALUE_TEST_UNITESTER_INT =
+UNIVALUE_TEST_UNITESTER_INT += %reldir%/test/unitester.cpp
+
+UNIVALUE_TEST_JSON_INT =
+UNIVALUE_TEST_JSON_INT += %reldir%/test/test_json.cpp
+
+UNIVALUE_TEST_NO_NUL_INT =
+UNIVALUE_TEST_NO_NUL_INT += %reldir%/test/no_nul.cpp
+
+UNIVALUE_TEST_OBJECT_INT =
+UNIVALUE_TEST_OBJECT_INT += %reldir%/test/object.cpp
+
+UNIVALUE_TEST_FILES_INT =
+UNIVALUE_TEST_FILES_INT += %reldir%/test/fail1.json
+UNIVALUE_TEST_FILES_INT += %reldir%/test/fail2.json
+UNIVALUE_TEST_FILES_INT += %reldir%/test/fail3.json
+UNIVALUE_TEST_FILES_INT += %reldir%/test/fail4.json
+UNIVALUE_TEST_FILES_INT += %reldir%/test/fail5.json
+UNIVALUE_TEST_FILES_INT += %reldir%/test/fail6.json
+UNIVALUE_TEST_FILES_INT += %reldir%/test/fail7.json
+UNIVALUE_TEST_FILES_INT += %reldir%/test/fail8.json
+UNIVALUE_TEST_FILES_INT += %reldir%/test/fail9.json
+UNIVALUE_TEST_FILES_INT += %reldir%/test/fail10.json
+UNIVALUE_TEST_FILES_INT += %reldir%/test/fail11.json
+UNIVALUE_TEST_FILES_INT += %reldir%/test/fail12.json
+UNIVALUE_TEST_FILES_INT += %reldir%/test/fail13.json
+UNIVALUE_TEST_FILES_INT += %reldir%/test/fail14.json
+UNIVALUE_TEST_FILES_INT += %reldir%/test/fail15.json
+UNIVALUE_TEST_FILES_INT += %reldir%/test/fail16.json
+UNIVALUE_TEST_FILES_INT += %reldir%/test/fail17.json
+UNIVALUE_TEST_FILES_INT += %reldir%/test/fail18.json
+UNIVALUE_TEST_FILES_INT += %reldir%/test/fail19.json
+UNIVALUE_TEST_FILES_INT += %reldir%/test/fail20.json
+UNIVALUE_TEST_FILES_INT += %reldir%/test/fail21.json
+UNIVALUE_TEST_FILES_INT += %reldir%/test/fail22.json
+UNIVALUE_TEST_FILES_INT += %reldir%/test/fail23.json
+UNIVALUE_TEST_FILES_INT += %reldir%/test/fail24.json
+UNIVALUE_TEST_FILES_INT += %reldir%/test/fail25.json
+UNIVALUE_TEST_FILES_INT += %reldir%/test/fail26.json
+UNIVALUE_TEST_FILES_INT += %reldir%/test/fail27.json
+UNIVALUE_TEST_FILES_INT += %reldir%/test/fail28.json
+UNIVALUE_TEST_FILES_INT += %reldir%/test/fail29.json
+UNIVALUE_TEST_FILES_INT += %reldir%/test/fail30.json
+UNIVALUE_TEST_FILES_INT += %reldir%/test/fail31.json
+UNIVALUE_TEST_FILES_INT += %reldir%/test/fail32.json
+UNIVALUE_TEST_FILES_INT += %reldir%/test/fail33.json
+UNIVALUE_TEST_FILES_INT += %reldir%/test/fail34.json
+UNIVALUE_TEST_FILES_INT += %reldir%/test/fail35.json
+UNIVALUE_TEST_FILES_INT += %reldir%/test/fail36.json
+UNIVALUE_TEST_FILES_INT += %reldir%/test/fail37.json
+UNIVALUE_TEST_FILES_INT += %reldir%/test/fail38.json
+UNIVALUE_TEST_FILES_INT += %reldir%/test/fail39.json
+UNIVALUE_TEST_FILES_INT += %reldir%/test/fail40.json
+UNIVALUE_TEST_FILES_INT += %reldir%/test/fail41.json
+UNIVALUE_TEST_FILES_INT += %reldir%/test/fail42.json
+UNIVALUE_TEST_FILES_INT += %reldir%/test/fail44.json
+UNIVALUE_TEST_FILES_INT += %reldir%/test/fail45.json
+UNIVALUE_TEST_FILES_INT += %reldir%/test/pass1.json
+UNIVALUE_TEST_FILES_INT += %reldir%/test/pass2.json
+UNIVALUE_TEST_FILES_INT += %reldir%/test/pass3.json
+UNIVALUE_TEST_FILES_INT += %reldir%/test/pass4.json
+UNIVALUE_TEST_FILES_INT += %reldir%/test/round1.json
+UNIVALUE_TEST_FILES_INT += %reldir%/test/round2.json
+UNIVALUE_TEST_FILES_INT += %reldir%/test/round3.json
+UNIVALUE_TEST_FILES_INT += %reldir%/test/round4.json
+UNIVALUE_TEST_FILES_INT += %reldir%/test/round5.json
+UNIVALUE_TEST_FILES_INT += %reldir%/test/round6.json
+UNIVALUE_TEST_FILES_INT += %reldir%/test/round7.json
diff --git a/src/univalue/test/object.cpp b/src/univalue/test/object.cpp
index ccc13448364a7..c2f52f83ac217 100644
--- a/src/univalue/test/object.cpp
+++ b/src/univalue/test/object.cpp
@@ -1,7 +1,7 @@
 // Copyright (c) 2014 BitPay Inc.
 // Copyright (c) 2014-2016 The Bitcoin Core developers
 // Distributed under the MIT software license, see the accompanying
-// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+// file COPYING or https://opensource.org/licenses/mit-license.php.
 
 #include <stdint.h>
 #include <vector>
diff --git a/src/univalue/test/unitester.cpp b/src/univalue/test/unitester.cpp
index 2308afbcdf037..02e1a83c6dffa 100644
--- a/src/univalue/test/unitester.cpp
+++ b/src/univalue/test/unitester.cpp
@@ -1,6 +1,6 @@
 // Copyright 2014 BitPay Inc.
 // Distributed under the MIT/X11 software license, see the accompanying
-// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+// file COPYING or https://opensource.org/licenses/mit-license.php.
 
 #include <stdlib.h>
 #include <stdio.h>
@@ -58,7 +58,7 @@ static void runtest_file(const char *filename_)
         std::string basename(filename_);
         std::string filename = srcdir + "/" + basename;
         FILE *f = fopen(filename.c_str(), "r");
-        assert(f != NULL);
+        assert(f != nullptr);
 
         std::string jdata;