diff --git a/libavformat/id3v2.c b/libavformat/id3v2.c
index 6d32731aca..03f70cc765 100644
--- a/libavformat/id3v2.c
+++ b/libavformat/id3v2.c
@@ -609,7 +609,10 @@ static void read_apic(AVFormatContext *s, AVIOContext *pb, int taglen,
 
     /* mimetype */
     if (isv34) {
-        taglen -= avio_get_str(pb, taglen, mimetype, sizeof(mimetype));
+        int ret = avio_get_str(pb, taglen, mimetype, sizeof(mimetype));
+        if (ret < 0 || ret >= taglen)
+            goto fail;
+        taglen -= ret;
     } else {
         if (avio_read(pb, mimetype, 3) < 0)
             goto fail;