diff --git a/libavformat/assdec.c b/libavformat/assdec.c
index 82e6a712d7..32fb09d22d 100644
--- a/libavformat/assdec.c
+++ b/libavformat/assdec.c
@@ -143,7 +143,7 @@ static int read_header(AVFormatContext *s, AVFormatParameters *ap)
         p++;
     }
 
-    qsort(ass->event, ass->event_count, sizeof(*ass->event), event_cmp);
+    qsort(ass->event, ass->event_count, sizeof(*ass->event), (void*)event_cmp);
 
     return 0;