diff --git a/tools/testing/selftests/ftrace/test.d/functions b/tools/testing/selftests/ftrace/test.d/functions
index f68d336b961b6..000fd05e84b16 100644
--- a/tools/testing/selftests/ftrace/test.d/functions
+++ b/tools/testing/selftests/ftrace/test.d/functions
@@ -137,7 +137,7 @@ check_requires() { # Check required files and tracers
                 echo "Required tracer $t is not configured."
                 exit_unsupported
             fi
-        elif [ $r != $i ]; then
+        elif [ "$r" != "$i" ]; then
             if ! grep -Fq "$r" README ; then
                 echo "Required feature pattern \"$r\" is not in README."
                 exit_unsupported