diff --git a/libavcodec/ffv1dec_template.c b/libavcodec/ffv1dec_template.c
index 21af155bba..892ccf22fa 100644
--- a/libavcodec/ffv1dec_template.c
+++ b/libavcodec/ffv1dec_template.c
@@ -96,7 +96,7 @@ static av_always_inline void RENAME(decode_line)(FFV1Context *s, int w,
         }
 
         if (sign)
-            diff = -diff;
+            diff = -(unsigned)diff;
 
         sample[1][x] = av_mod_uintp2(RENAME(predict)(sample[1] + x, sample[0] + x) + diff, bits);
     }