diff --git a/porting/liteos_m/kernel/src/stdio/fopen.c b/porting/liteos_m/kernel/src/stdio/fopen.c
index 7dddf930b1b81c23730b004a3f7afb4ca98a76d0..56086846694651fc00472262b7b3a9c8d99a3a7c 100644
--- a/porting/liteos_m/kernel/src/stdio/fopen.c
+++ b/porting/liteos_m/kernel/src/stdio/fopen.c
@@ -12,7 +12,7 @@ FILE *fopen(const char *restrict filename, const char *restrict mode)
 	int flags;
 
 	/* Check for valid initial mode character */
-	if (!strchr("rwa", *mode)) {
+	if ((mode == NULL) || (!strchr("rwa", *mode))) {
 		errno = EINVAL;
 		return 0;
 	}