diff --git a/tests/scripts/quiet/quiet.sh b/tests/scripts/quiet/quiet.sh
index 0f5bf06ecd..be065f4d78 100755
--- a/tests/scripts/quiet/quiet.sh
+++ b/tests/scripts/quiet/quiet.sh
@@ -1,3 +1,5 @@
+# -*-mode: sh; sh-shell: bash -*-
+#
 # Copyright The Mbed TLS Contributors
 # SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
 #