diff --git a/.travis.yml b/.travis.yml
index 27bd1b9..350bf13 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -274,7 +274,8 @@ install:
 script:
   - |-
     echo "using $TOOLSET : : $COMPILER ;" > ~/user-config.jam
-  - ./b2 -j 3 libs/core/test toolset=$TOOLSET cxxstd=$CXXSTD variant=debug,release ${UBSAN:+cxxflags=-fsanitize=undefined cxxflags=-fno-sanitize-recover=undefined linkflags=-fsanitize=undefined define=UBSAN=1 debug-symbols=on} ${LINKFLAGS:+linkflags=$LINKFLAGS}
+  - BUILD_JOBS=`(nproc || sysctl -n hw.ncpu) 2> /dev/null`
+  - ./b2 -j $BUILD_JOBS libs/core/test toolset=$TOOLSET cxxstd=$CXXSTD variant=debug,release ${UBSAN:+cxxflags=-fsanitize=undefined cxxflags=-fno-sanitize-recover=undefined linkflags=-fsanitize=undefined define=UBSAN=1 debug-symbols=on} ${LINKFLAGS:+linkflags=$LINKFLAGS}
 
 notifications:
   email:
diff --git a/appveyor.yml b/appveyor.yml
index 3664a15..14c8b42 100644
--- a/appveyor.yml
+++ b/appveyor.yml
@@ -73,4 +73,4 @@ build: off
 test_script:
   - PATH=%ADDPATH%%PATH%
   - if not "%CXXSTD%" == "" set CXXSTD=cxxstd=%CXXSTD%
-  - b2 -j 3 libs/core/test toolset=%TOOLSET% %CXXSTD%
+  - b2 -j %NUMBER_OF_PROCESSORS% libs/core/test toolset=%TOOLSET% %CXXSTD%