diff --git a/fs/squashfs/zlib_wrapper.c b/fs/squashfs/zlib_wrapper.c
index 15a03d0..7a60387 100644
--- a/fs/squashfs/zlib_wrapper.c
+++ b/fs/squashfs/zlib_wrapper.c
@@ -128,8 +128,9 @@
 		goto release_mutex;
 	}
 
+	length = stream->total_out;
 	mutex_unlock(&msblk->read_data_mutex);
-	return stream->total_out;
+	return length;
 
 release_mutex:
 	mutex_unlock(&msblk->read_data_mutex);