diff --git a/libavformat/swfenc.c b/libavformat/swfenc.c
index 6a3cdad09e..f56c58017b 100644
--- a/libavformat/swfenc.c
+++ b/libavformat/swfenc.c
@@ -21,6 +21,7 @@
  */
 
 #include "libavcodec/put_bits.h"
+#include "libavutil/avassert.h"
 #include "avformat.h"
 #include "swf.h"
 
@@ -56,7 +57,7 @@ static void put_swf_end_tag(AVFormatContext *s)
         avio_wl16(pb, (tag << 6) | 0x3f);
         avio_wl32(pb, tag_len - 4);
     } else {
-        assert(tag_len < 0x3f);
+        av_assert0(tag_len < 0x3f);
         avio_wl16(pb, (tag << 6) | tag_len);
     }
     avio_seek(pb, pos, SEEK_SET);