diff --git a/libavformat/matroskadec.c b/libavformat/matroskadec.c
index 2a88fc3db4..6330b15ecf 100644
--- a/libavformat/matroskadec.c
+++ b/libavformat/matroskadec.c
@@ -1980,11 +1980,19 @@ static int matroska_parse_block(MatroskaDemuxContext *matroska, uint8_t *data,
                         }
                         total += lace_size[n];
                     }
+                    if (size <= total) {
+                        res = AVERROR_INVALIDDATA;
+                        goto end;
+                    }
                     lace_size[n] = size - total;
                     break;
                 }
 
                 case 0x2: /* fixed-size lacing */
+                    if (size != (size / laces) * size) {
+                        res = AVERROR_INVALIDDATA;
+                        goto end;
+                    }
                     for (n = 0; n < laces; n++)
                         lace_size[n] = size / laces;
                     break;
@@ -1995,7 +2003,8 @@ static int matroska_parse_block(MatroskaDemuxContext *matroska, uint8_t *data,
                     if (n < 0) {
                         av_log(matroska->ctx, AV_LOG_INFO,
                                "EBML block data error\n");
-                        break;
+                        res = n;
+                        goto end;
                     }
                     data += n;
                     size -= n;
@@ -2007,13 +2016,18 @@ static int matroska_parse_block(MatroskaDemuxContext *matroska, uint8_t *data,
                         if (r < 0) {
                             av_log(matroska->ctx, AV_LOG_INFO,
                                    "EBML block data error\n");
-                            break;
+                            res = r;
+                            goto end;
                         }
                         data += r;
                         size -= r;
                         lace_size[n] = lace_size[n - 1] + snum;
                         total += lace_size[n];
                     }
+                    if (size <= total) {
+                        res = AVERROR_INVALIDDATA;
+                        goto end;
+                    }
                     lace_size[laces - 1] = size - total;
                     break;
                 }