diff --git a/libavformat/matroskadec.c b/libavformat/matroskadec.c
index 2aa686af44..2ffd8e62fb 100644
--- a/libavformat/matroskadec.c
+++ b/libavformat/matroskadec.c
@@ -1399,7 +1399,7 @@ static int matroska_decode_buffer(uint8_t **buf, int *buf_size,
     case MATROSKA_TRACK_ENCODING_COMP_ZLIB:
     {
         z_stream zstream = { 0 };
-        if (inflateInit(&zstream) != Z_OK)
+        if (!pkt_size || inflateInit(&zstream) != Z_OK)
             return -1;
         zstream.next_in  = data;
         zstream.avail_in = isize;
@@ -1432,7 +1432,7 @@ static int matroska_decode_buffer(uint8_t **buf, int *buf_size,
     case MATROSKA_TRACK_ENCODING_COMP_BZLIB:
     {
         bz_stream bzstream = { 0 };
-        if (BZ2_bzDecompressInit(&bzstream, 0, 0) != BZ_OK)
+        if (!pkt_size || BZ2_bzDecompressInit(&bzstream, 0, 0) != BZ_OK)
             return -1;
         bzstream.next_in  = data;
         bzstream.avail_in = isize;