diff --git a/libavcodec/dvdsubdec.c b/libavcodec/dvdsubdec.c
index ed80b718d5..917adc3dfe 100644
--- a/libavcodec/dvdsubdec.c
+++ b/libavcodec/dvdsubdec.c
@@ -60,7 +60,7 @@ static void yuv_a_to_rgba(const uint8_t *ycbcr, const uint8_t *alpha, uint32_t *
         cb = *ycbcr++;
         YUV_TO_RGB1_CCIR(cb, cr);
         YUV_TO_RGB2_CCIR(r, g, b, y);
-        *rgba++ = (*alpha++ << 24) | (r << 16) | (g << 8) | b;
+        *rgba++ = ((unsigned)*alpha++ << 24) | (r << 16) | (g << 8) | b;
     }
 }