diff --git a/src/lib_ccx/matroska.c b/src/lib_ccx/matroska.c
index 3b3d8a815..7f5e9a87a 100644
--- a/src/lib_ccx/matroska.c
+++ b/src/lib_ccx/matroska.c
@@ -1898,12 +1898,24 @@ void free_sub_track(struct matroska_sub_track *track)
 		free(track->lang_ietf);
 	if (track->codec_id_string != NULL)
 		free(track->codec_id_string);
-	for (int i = 0; i < track->sentence_count; i++)
-	{
-		struct matroska_sub_sentence *sentence = track->sentences[i];
-		free(sentence->text);
-		free(sentence);
-	}
+for (int i = 0; i < track->sentence_count; i++)
+{
+    struct matroska_sub_sentence *sentence = track->sentences[i];
+	
+    free(sentence->text);
+		
+    if (sentence->blockaddition != NULL)
+    {
+        /* cue_settings_list is the base of the message buffer;
+         * cue_identifier and comment are pointers into it */
+        if (sentence->blockaddition->cue_settings_list != NULL)
+		{
+       		free(sentence->blockaddition->cue_settings_list);
+		}
+        free(sentence->blockaddition);
+    }
+    free(sentence);
+
 	if (track->sentences != NULL)
 		free(track->sentences);
 	free(track);