diff --git a/lib/persistence.migrations.js b/lib/persistence.migrations.js
index 97b93aa..5cbbc89 100644
--- a/lib/persistence.migrations.js
+++ b/lib/persistence.migrations.js
@@ -138,8 +138,10 @@ if(!window.persistence) { // persistence.js not loaded!
       },
       
       migrate: function(version, callback) {
-        if ( arguments.length === 1 ) {
+        if ( arguments.length === 1) {
           callback = version;
+        }
+        if ( arguments.length <= 1) {
           version = this.migrations.length-1;
         }