diff --git a/index.js b/index.js
index b797184..92bca53 100644
--- a/index.js
+++ b/index.js
@@ -50,7 +50,7 @@ exports.getDiskSize = function (callback) {
 
   if (db.type() === 'leveldb') {
     var prefix = db.__opts.prefix || '';
-    var path = prefix + db._db_name;
+    var path = prefix + (db.name || db._db_name); // '_db_name' for pouchdb 5.x.
 
     // wait until the database is ready. Necessary for at least sqldown,
     // which doesn't write anything to disk sooner.