diff --git a/do_cmake.sh b/do_cmake.sh
index e583c23732472..15cc01242fd8c 100755
--- a/do_cmake.sh
+++ b/do_cmake.sh
@@ -12,13 +12,12 @@ fi
 
 mkdir build
 cd build
-NPROC=${NPROC:-$(nproc)}
 if type cmake3 > /dev/null 2>&1 ; then
     CMAKE=cmake3
 else
     CMAKE=cmake
 fi
-${CMAKE} -DBOOST_J=$NPROC $ARGS "$@" .. || exit 1
+${CMAKE} $ARGS "$@" .. || exit 1
 
 # minimal config to find plugins
 cat <<EOF > ceph.conf
diff --git a/run-make-check.sh b/run-make-check.sh
index be52f5fa1e412..a3a50dfd58390 100755
--- a/run-make-check.sh
+++ b/run-make-check.sh
@@ -55,6 +55,8 @@ function detect_ceph_dev_pkgs() {
     local boost_root=/opt/ceph
     if test -f $boost_root/include/boost/config.hpp; then
         cmake_opts+=" -DWITH_SYSTEM_BOOST=ON -DBOOST_ROOT=$boost_root"
+    else
+        cmake_opts+=" -DBOOST_J=$(get_processors)"
     fi
     echo "$cmake_opts"
 }