diff --git a/tools/run_tests/run_lcov.sh b/tools/run_tests/run_lcov.sh
index 6f22b0e8a4110389edecf92801448a80c1281a03..068213a3d29935765c81015af24904dd85978d64 100755
--- a/tools/run_tests/run_lcov.sh
+++ b/tools/run_tests/run_lcov.sh
@@ -7,7 +7,7 @@ out=`realpath ${1:-coverage}`
 root=`realpath $(dirname $0)/../..`
 tmp=`mktemp`
 cd $root
-tools/run_tests/run_tests.py -c gcov
+tools/run_tests/run_tests.py -c gcov -l c c++
 lcov --capture --directory . --output-file $tmp
 genhtml $tmp --output-directory $out
 rm $tmp