diff --git a/libavformat/aiffdec.c b/libavformat/aiffdec.c
index d7a37fe207..1bd073841d 100644
--- a/libavformat/aiffdec.c
+++ b/libavformat/aiffdec.c
@@ -73,7 +73,7 @@ static int get_tag(AVIOContext *pb, uint32_t * tag)
 /* Metadata string read */
 static void get_meta(AVFormatContext *s, const char *key, int size)
 {
-    uint8_t *str = av_malloc(size+1);
+    uint8_t *str = av_malloc(size+1U);
 
     if (str) {
         int res = avio_read(s->pb, str, size);