diff --git a/libavcodec/sunrast.c b/libavcodec/sunrast.c
index 36dfa98293..0f637399ef 100644
--- a/libavcodec/sunrast.c
+++ b/libavcodec/sunrast.c
@@ -135,7 +135,7 @@ static int sunrast_decode_frame(AVCodecContext *avctx, void *data,
 
         ptr = p->data[1];
         for (x=0; x<len; x++, ptr+=4)
-            *(uint32_t *)ptr = (buf[x]<<16) + (buf[len+x]<<8) + buf[len+len+x];
+            *(uint32_t *)ptr = (0xFF<<24) + (buf[x]<<16) + (buf[len+x]<<8) + buf[len+len+x];
     }
 
     buf += maplength;