diff --git a/block.c b/block.c
index e2d9936..d7ca37e 100644
--- a/block.c
+++ b/block.c
@@ -824,8 +824,8 @@
 
 #ifndef _WIN32
     if (bs->is_temporary) {
-        assert(filename != NULL);
-        unlink(filename);
+        assert(bs->filename[0] != '\0');
+        unlink(bs->filename);
     }
 #endif
     return 0;