diff --git a/libavformat/aviobuf.c b/libavformat/aviobuf.c
index 6923b78ea1..5f848b20f9 100644
--- a/libavformat/aviobuf.c
+++ b/libavformat/aviobuf.c
@@ -206,7 +206,7 @@ int64_t avio_seek(AVIOContext *s, int64_t offset, int whence)
     }
     offset1 = offset - pos;
     if (!s->must_flush &&
-        offset1 >= 0 && offset1 <= (s->buf_end - s->buffer)) {
+        offset1 >= 0 && offset1 < (s->buf_end - s->buffer)) {
         /* can do the seek inside the buffer */
         s->buf_ptr = s->buffer + offset1;
     } else if ((!s->seekable ||