diff --git a/libavformat/rtpenc_h264.c b/libavformat/rtpenc_h264.c
index ac74074307..206d9bafa3 100644
--- a/libavformat/rtpenc_h264.c
+++ b/libavformat/rtpenc_h264.c
@@ -31,14 +31,14 @@
 
 static const uint8_t *avc_mp4_find_startcode(const uint8_t *start, const uint8_t *end, int nal_length_size)
 {
-    int res = 0;
+    unsigned int res = 0;
 
     if (end - start < nal_length_size)
         return NULL;
     while (nal_length_size--)
         res = (res << 8) | *start++;
 
-    if (start + res > end || res < 0 || start + res < start)
+    if (res > end - start)
         return NULL;
 
     return start + res;