diff --git a/tools/buildrocks.sh b/tools/buildrocks.sh
index 2bdefa062..a03ecd382 100755
--- a/tools/buildrocks.sh
+++ b/tools/buildrocks.sh
@@ -48,5 +48,6 @@ run git submodule update --init deps/rocksdb
 
 run cd deps/rocksdb
 run git checkout $BRANCH
-CFLAGS="-fPIC -frtti -DROCKSDB_USE_RTTI" run make -j4 $LINKAGE
+NJOBS=`nproc`
+CFLAGS="-fPIC -frtti -DROCKSDB_USE_RTTI" run make -j$NJOBS $LINKAGE
 run cd $USERDIR         # Return to user's original directory