diff --git a/libavcodec/qdm2.c b/libavcodec/qdm2.c
index 776a9e9f45..5ceec3420d 100644
--- a/libavcodec/qdm2.c
+++ b/libavcodec/qdm2.c
@@ -1727,8 +1727,8 @@ static av_cold int qdm2_decode_init(AVCodecContext *avctx)
     extradata += 4;
 
     s->checksum_size = AV_RB32(extradata);
-    if (s->checksum_size >= 1U << 28) {
-        av_log(avctx, AV_LOG_ERROR, "data block size too large (%u)\n", s->checksum_size);
+    if (s->checksum_size >= 1U << 28 || !s->checksum_size) {
+        av_log(avctx, AV_LOG_ERROR, "data block size invalid (%u)\n", s->checksum_size);
         return AVERROR_INVALIDDATA;
     }