diff --git a/libavcodec/wmv2dsp.c b/libavcodec/wmv2dsp.c
index cfa25f08dc..7b59d10a43 100644
--- a/libavcodec/wmv2dsp.c
+++ b/libavcodec/wmv2dsp.c
@@ -48,8 +48,8 @@ static void wmv2_idct_row(short * b)
     a4 = W0 * b[0] - W0 * b[4];
 
     /* step 2 */
-    s1 = (181 * (a1 - a5 + a7 - a3) + 128) >> 8; // 1, 3, 5, 7
-    s2 = (181 * (a1 - a5 - a7 + a3) + 128) >> 8;
+    s1 = (int)(181U * (a1 - a5 + a7 - a3) + 128) >> 8; // 1, 3, 5, 7
+    s2 = (int)(181U * (a1 - a5 - a7 + a3) + 128) >> 8;
 
     /* step 3 */
     b[0] = (a0 + a2 + a1 + a5 + (1 << 7)) >> 8;