diff --git a/tests/kernel/fatal/src/main.c b/tests/kernel/fatal/src/main.c
index 14ae937a05d..46f310f58b8 100644
--- a/tests/kernel/fatal/src/main.c
+++ b/tests/kernel/fatal/src/main.c
@@ -82,7 +82,7 @@ void alt_thread1(void)
 	 * and xtensa
 	 */
 	{
-		long illegal = 0;
+		volatile long illegal = 0;
 		((void(*)(void))&illegal)();
 	}
 #endif