diff --git a/libavcodec/texturedsp.c b/libavcodec/texturedsp.c
index 49e97c91ae..90b1eb4f11 100644
--- a/libavcodec/texturedsp.c
+++ b/libavcodec/texturedsp.c
@@ -158,7 +158,7 @@ static inline void dxt3_block_internal(uint8_t *dst, ptrdiff_t stride,
 
         for (x = 0; x < 4; x++) {
             uint8_t alpha = alpha_values[x];
-            uint32_t pixel = colors[code & 3] | (alpha << 24);
+            uint32_t pixel = colors[code & 3] | ((unsigned)alpha << 24);
             code >>= 2;
 
             AV_WL32(dst + x * 4, pixel);