diff --git a/CMakeLists.txt b/CMakeLists.txt
index 47ac8950..7613cc18 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -14,10 +14,6 @@ if(PROJECT_SOURCE_DIR STREQUAL PROJECT_BINARY_DIR)
     message(FATAL_ERROR "In-source builds not allowed. Please make a new directory (called a build directory) and run CMake from there.")
 endif()
 
-# --- Import tools ----
-
-include(cmake/tools.cmake)
-
 # ---- Add dependencies via CPM ----
 # see https://github.com/TheLartians/CPM.cmake for more info
 
diff --git a/cmake/CPM.cmake b/cmake/CPM.cmake
index d5bdba0d..1b859ce7 100644
--- a/cmake/CPM.cmake
+++ b/cmake/CPM.cmake
@@ -28,7 +28,7 @@
 
 cmake_minimum_required(VERSION 3.14 FATAL_ERROR)
 
-set(CURRENT_CPM_VERSION 0.18)
+set(CURRENT_CPM_VERSION 0.21)
 
 if(CPM_DIRECTORY)
   if(NOT ${CPM_DIRECTORY} MATCHES ${CMAKE_CURRENT_LIST_DIR})
@@ -41,14 +41,23 @@ See https://github.com/TheLartians/CPM.cmake for more information."
     endif()
     return()
   endif()
+
+  get_property(CPM_INITIALIZED GLOBAL "" PROPERTY CPM_INITIALIZED SET)   
+  if (CPM_INITIALIZED)
+    return()
+  endif()
 endif()
 
+set_property(GLOBAL PROPERTY CPM_INITIALIZED true) 
+
 option(CPM_USE_LOCAL_PACKAGES "Always try to use `find_package` to get dependencies" $ENV{CPM_USE_LOCAL_PACKAGES})
 option(CPM_LOCAL_PACKAGES_ONLY "Only use `find_package` to get dependencies" $ENV{CPM_LOCAL_PACKAGES_ONLY})
 option(CPM_DOWNLOAD_ALL "Always download dependencies from source" $ENV{CPM_DOWNLOAD_ALL})
+option(CPM_DONT_UPDATE_MODULE_PATH "Don't update the module path to allow using find_package" $ENV{CPM_DONT_UPDATE_MODULE_PATH})
 
 set(CPM_VERSION ${CURRENT_CPM_VERSION} CACHE INTERNAL "")
 set(CPM_DIRECTORY ${CMAKE_CURRENT_LIST_DIR} CACHE INTERNAL "")
+set(CPM_FILE ${CMAKE_CURRENT_LIST_FILE} CACHE INTERNAL "")
 set(CPM_PACKAGES "" CACHE INTERNAL "")
 set(CPM_DRY_RUN OFF CACHE INTERNAL "Don't download or configure dependencies (for testing)")
 
@@ -60,6 +69,15 @@ endif()
 
 set(CPM_SOURCE_CACHE ${CPM_SOURCE_CACHE_DEFAULT} CACHE PATH "Directory to downlaod CPM dependencies")
 
+if (NOT CPM_DONT_UPDATE_MODULE_PATH)
+  set(CPM_MODULE_PATH "${CMAKE_BINARY_DIR}/CPM_modules" CACHE INTERNAL "")
+  # remove old modules
+  FILE(REMOVE_RECURSE ${CPM_MODULE_PATH})
+  file(MAKE_DIRECTORY ${CPM_MODULE_PATH})
+  # locally added CPM modules should override global packages
+  set(CMAKE_MODULE_PATH "${CPM_MODULE_PATH};${CMAKE_MODULE_PATH}")
+endif()
+
 include(FetchContent)
 include(CMakeParseArguments)
 
@@ -80,6 +98,15 @@ function(cpm_find_package NAME VERSION)
   endif()
 endfunction()
 
+# Create a custom FindXXX.cmake module for a CPM package
+# This prevents `find_package(NAME)` from finding the system library
+function(CPMCreateModuleFile Name)
+  if (NOT CPM_DONT_UPDATE_MODULE_PATH)
+    # erase any previous modules
+    FILE(WRITE ${CPM_MODULE_PATH}/Find${Name}.cmake "include(${CPM_FILE})\n${ARGN}\nset(${Name}_FOUND TRUE)")
+  endif()
+endfunction()
+
 # Find a package locally or fallback to CPMAddPackage
 function(CPMFindPackage)
   set(oneValueArgs
@@ -167,7 +194,7 @@ function(CPMAddPackage)
     list(APPEND CPM_ARGS_UNPARSED_ARGUMENTS GIT_REPOSITORY "https://gitlab.com/${CPM_ARGS_GITLAB_REPOSITORY}.git")
   endif()
 
-  if (${CPM_ARGS_NAME} IN_LIST CPM_PACKAGES)
+  if ("${CPM_ARGS_NAME}" IN_LIST CPM_PACKAGES)
     CPMGetPackageVersion(${CPM_ARGS_NAME} CPM_PACKAGE_VERSION)
     if(${CPM_PACKAGE_VERSION} VERSION_LESS ${CPM_ARGS_VERSION})
       message(WARNING "${CPM_INDENT} requires a newer version of ${CPM_ARGS_NAME} (${CPM_ARGS_VERSION}) than currently included (${CPM_PACKAGE_VERSION}).")
@@ -218,7 +245,8 @@ function(CPMAddPackage)
     set(download_directory ${CPM_SOURCE_CACHE}/${lower_case_name}/${origin_hash})
     list(APPEND FETCH_CONTENT_DECLARE_EXTRA_OPTS SOURCE_DIR ${download_directory})
     if (EXISTS ${download_directory})
-      list(APPEND FETCH_CONTENT_DECLARE_EXTRA_OPTS DOWNLOAD_COMMAND ":")
+      # disable the download command to allow offline builds
+      list(APPEND FETCH_CONTENT_DECLARE_EXTRA_OPTS DOWNLOAD_COMMAND "${CMAKE_COMMAND}")
       set(PACKAGE_INFO "${download_directory}")
     else()
       # remove timestamps so CMake will re-download the dependency
@@ -230,6 +258,7 @@ function(CPMAddPackage)
   cpm_declare_fetch(${CPM_ARGS_NAME} ${CPM_ARGS_VERSION} ${PACKAGE_INFO} "${CPM_ARGS_UNPARSED_ARGUMENTS}" ${FETCH_CONTENT_DECLARE_EXTRA_OPTS})
   cpm_fetch_package(${CPM_ARGS_NAME} ${DOWNLOAD_ONLY})
   cpm_get_fetch_properties(${CPM_ARGS_NAME})
+  CPMCreateModuleFile(${CPM_ARGS_NAME} "CPMAddPackage(${ARGN})")
   SET(${CPM_ARGS_NAME}_ADDED YES)
   cpm_export_variables()
 endfunction()
diff --git a/cmake/tools.cmake b/cmake/tools.cmake
index 31ec37cf..2f2e595b 100644
--- a/cmake/tools.cmake
+++ b/cmake/tools.cmake
@@ -1,16 +1,16 @@
 # this file contains a list of tools that can be activated and downloaded on-demand
 # each tool is enabled during configuration by passing an additional `-DUSE_<TOOL>=<VALUE>` argument to CMake
 
-# determine if a tool has already been enabled
-foreach(TOOL USE_SANITIZER;USE_CCACHE)
-  get_property(${TOOL}_ENABLED GLOBAL "" PROPERTY ${TOOL}_ENABLED SET)   
-endforeach()
+# only activate tools for top level project
+if (NOT PROJECT_SOURCE_DIR STREQUAL CMAKE_SOURCE_DIR)
+  return()
+endif()
+
+include(${CMAKE_CURRENT_LIST_DIR}/CPM.cmake)
 
 # enables sanitizers support using the the `USE_SANITIZER` flag
 # available values are: Address, Memory, MemoryWithOrigins, Undefined, Thread, Leak, 'Address;Undefined'
-if (USE_SANITIZER AND NOT USE_SANITIZER_ENABLED)
-  set_property(GLOBAL PROPERTY USE_SANITIZER_ENABLED true) 
-
+if (USE_SANITIZER)
   CPMAddPackage(
     NAME StableCoder-cmake-scripts
     GITHUB_REPOSITORY StableCoder/cmake-scripts
@@ -22,9 +22,7 @@ endif()
 
 # enables CCACHE support through the USE_CCACHE flag
 # possible values are: YES, NO or equivalent
-if (USE_CCACHE AND NOT USE_CCACHE_ENABLED)
-  set_property(GLOBAL PROPERTY USE_CCACHE_ENABLED true) 
-
+if (USE_CCACHE)
   CPMAddPackage(
     NAME Ccache.cmake
     GITHUB_REPOSITORY TheLartians/Ccache.cmake
diff --git a/standalone/CMakeLists.txt b/standalone/CMakeLists.txt
index cd81e5ae..19a4993f 100644
--- a/standalone/CMakeLists.txt
+++ b/standalone/CMakeLists.txt
@@ -4,6 +4,10 @@ project(GreeterStandalone
   LANGUAGES CXX
 )
 
+# --- Import tools ----
+
+include(../cmake/tools.cmake)
+
 # ---- Dependencies ----
 
 include(../cmake/CPM.cmake)
diff --git a/test/CMakeLists.txt b/test/CMakeLists.txt
index 4b276ed8..123fd8d2 100644
--- a/test/CMakeLists.txt
+++ b/test/CMakeLists.txt
@@ -9,6 +9,10 @@ project(GreeterTests
 option(ENABLE_TEST_COVERAGE "Enable test coverage" OFF)
 option(TEST_INSTALLED_VERSION "Test the version found by find_package" OFF)
 
+# --- Import tools ----
+
+include(../cmake/tools.cmake)
+
 # ---- Dependencies ----
 
 include(../cmake/CPM.cmake)