diff --git a/lib/jsonrpc.js b/lib/jsonrpc.js
index 1ca9f8b..32873ad 100644
--- a/lib/jsonrpc.js
+++ b/lib/jsonrpc.js
@@ -196,7 +196,7 @@ Server.prototype.handlePOST = function(req, res) {
     // Try to call the method, but intercept errors and call our
     // onFailure handler.
     var method = self.functions[decoded.method];
-    var args = decoded.params.push(function(resp) {
+    var args = decoded.params.unshift(function(resp) {
       onSuccess(resp);
     });