diff --git a/lib/libc/snprintf.c b/lib/libc/snprintf.c
index 9bc07b2..66a2fa2 100644
--- a/lib/libc/snprintf.c
+++ b/lib/libc/snprintf.c
@@ -4,6 +4,7 @@
  * SPDX-License-Identifier: BSD-3-Clause
  */
 
+#include <assert.h>
 #include <debug.h>
 #include <platform.h>
 #include <stdarg.h>
@@ -117,6 +118,7 @@
 				ERROR("snprintf: specifier with ASCII code '%d' not supported.",
 				      *fmt);
 				plat_panic_handler();
+				assert(0); /* Unreachable */
 			}
 			fmt++;
 			continue;