diff --git a/tools/testing/selftests/sysctl/sysctl.sh b/tools/testing/selftests/sysctl/sysctl.sh
index e0c8404da6b031f72a3b8c48132acf68c1cb890b..f51987d0d32dff6038735ed9ab3cf708be3eccf0 100755
--- a/tools/testing/selftests/sysctl/sysctl.sh
+++ b/tools/testing/selftests/sysctl/sysctl.sh
@@ -179,7 +179,7 @@ verify()
 
 verify_diff_w()
 {
-	echo "$TEST_STR" | diff -q -w -u - $1
+	echo "$TEST_STR" | diff -q -w -u - $1 > /dev/null
 	return $?
 }