--- a/core/storagemanager.lua	Fri Apr 19 16:14:06 2013 +0200
+++ b/core/storagemanager.lua	Mon Apr 22 11:54:15 2013 -0400
@@ -86,7 +86,7 @@
 	if not ret then
 		if err == "unsupported-store" then
 			log("debug", "Storage driver %s does not support store %s (%s), falling back to null driver",
-				driver_name, store, typ);
+				driver_name, store, typ or "<nil>");
 			ret = null_storage_driver;
 			err = nil;
 		end