diff --git a/lib/index.js b/lib/index.js
index 8b3288b..b840b13 100644
--- a/lib/index.js
+++ b/lib/index.js
@@ -910,7 +910,7 @@ Statement.prototype.drop = function(callback) {
 Statement.prototype.execute = function(transaction, params, callback){
     if (params instanceof Function) {
         callback = params;
-        params = null;
+        params = undefined;
     }
     this.connection.executeStatement(transaction, this, params, callback);
 };
@@ -1069,6 +1069,11 @@ Database.prototype.newStatement = function (query, callback) {
 };
 
 Database.prototype.execute = function(query, params, callback) {
+    if (params instanceof Function) {
+        callback = params;
+        params = undefined;
+    }
+
     this.connection.startTransaction(
         function(err, transaction) {
             if (err) {doError(err, callback); return}