diff --git a/libavcodec/ffv1dec_template.c b/libavcodec/ffv1dec_template.c
index 21af155bba..36cfba9560 100644
--- a/libavcodec/ffv1dec_template.c
+++ b/libavcodec/ffv1dec_template.c
@@ -98,7 +98,7 @@ static av_always_inline void RENAME(decode_line)(FFV1Context *s, int w,
         if (sign)
             diff = -diff;
 
-        sample[1][x] = av_mod_uintp2(RENAME(predict)(sample[1] + x, sample[0] + x) + diff, bits);
+        sample[1][x] = av_mod_uintp2(RENAME(predict)(sample[1] + x, sample[0] + x) + (SUINT)diff, bits);
     }
     s->run_index = run_index;
 }