diff --git a/libavcodec/bmvvideo.c b/libavcodec/bmvvideo.c
index 97f850dbae..cf7f0a0501 100644
--- a/libavcodec/bmvvideo.c
+++ b/libavcodec/bmvvideo.c
@@ -107,7 +107,7 @@ static int decode_bmv_frame(const uint8_t *source, int src_len, uint8_t *frame,
                     if (src < source || src >= source_end)
                         return AVERROR_INVALIDDATA;
                     shift += 2;
-                    val |= *src << shift;
+                    val |= (unsigned)*src << shift;
                     if (*src & 0xC)
                         break;
                 }