diff --git a/libavformat/mov.c b/libavformat/mov.c
index 03fd90e3d3..afef53b79a 100644
--- a/libavformat/mov.c
+++ b/libavformat/mov.c
@@ -162,7 +162,11 @@ static int mov_read_mac_string(MOVContext *c, AVIOContext *pb, int len,
 
     for (i = 0; i < len; i++) {
         uint8_t t, c = avio_r8(pb);
-        if (c < 0x80 && p < end)
+
+        if (p >= end)
+            continue;
+
+        if (c < 0x80)
             *p++ = c;
         else if (p < end)
             PUT_UTF8(mac_to_unicode[c-0x80], t, if (p < end) *p++ = t;);