diff --git a/libavcodec/cbs_mpeg2.c b/libavcodec/cbs_mpeg2.c
index 0cac29733e..8fb5375e3b 100644
--- a/libavcodec/cbs_mpeg2.c
+++ b/libavcodec/cbs_mpeg2.c
@@ -220,7 +220,7 @@ static int cbs_mpeg2_read_unit(CodedBitstreamContext *ctx,
             START(0xb8, MPEG2RawGroupOfPicturesHeader, group_of_pictures_header);
 #undef START
         default:
-            av_log(ctx->log_ctx, AV_LOG_ERROR, "Unknown start code %02x.\n",
+            av_log(ctx->log_ctx, AV_LOG_ERROR, "Unknown start code %"PRIx32".\n",
                    unit->type);
             return AVERROR_INVALIDDATA;
         }