diff --git a/tools/run_tests/post_tests_c.sh b/tools/run_tests/post_tests_c.sh
index 996c10a0705..f2f3ce9432d 100755
--- a/tools/run_tests/post_tests_c.sh
+++ b/tools/run_tests/post_tests_c.sh
@@ -32,9 +32,9 @@ set -ex
 
 if [ "$CONFIG" != "gcov" ] ; then exit ; fi
 
-root=`readlink -f $(dirname $0)/../..`
+root=$(readlink -f $(dirname $0)/../..)
 out=$root/reports/c_cxx_coverage
-tmp=`mktemp`
+tmp=$(mktemp)
 cd $root
 lcov --capture --directory . --output-file $tmp
 genhtml $tmp --output-directory $out
diff --git a/tools/run_tests/run_lcov.sh b/tools/run_tests/run_lcov.sh
index 62bbd8c24b7..a28ec138bb6 100755
--- a/tools/run_tests/run_lcov.sh
+++ b/tools/run_tests/run_lcov.sh
@@ -30,10 +30,10 @@
 
 set -ex
 
-out=`readlink -f ${1:-coverage}`
+out=$(readlink -f ${1:-coverage})
 
-root=`readlink -f $(dirname $0)/../..`
-tmp=`mktemp`
+root=$(readlink -f $(dirname $0)/../..)
+tmp=$(mktemp)
 cd $root
 tools/run_tests/run_tests.py -c gcov -l c c++ || true
 lcov --capture --directory . --output-file $tmp