diff --git a/libavcodec/h264_direct.c b/libavcodec/h264_direct.c
index cbb84665b3..66e54479d1 100644
--- a/libavcodec/h264_direct.c
+++ b/libavcodec/h264_direct.c
@@ -39,7 +39,12 @@ static int get_scale_factor(H264SliceContext *sl,
                             int poc, int poc1, int i)
 {
     int poc0 = sl->ref_list[0][i].poc;
-    int td = av_clip_int8(poc1 - poc0);
+    int64_t pocdiff = poc1 - (int64_t)poc0;
+    int td = av_clip_int8(pocdiff);
+
+    if (pocdiff != (int)pocdiff)
+        avpriv_request_sample(sl->h264->avctx, "pocdiff overflow\n");
+
     if (td == 0 || sl->ref_list[0][i].parent->long_ref) {
         return 256;
     } else {