diff --git a/kernel/gcov/fs.c b/kernel/gcov/fs.c
index 5c3086cad8f9..01520689b57c 100644
--- a/kernel/gcov/fs.c
+++ b/kernel/gcov/fs.c
@@ -99,7 +99,7 @@ struct gcov_iterator {
 	struct gcov_info *info;
 	size_t size;
 	loff_t pos;
-	char buffer[];
+	char buffer[] __counted_by(size);
 };
 
 /**