diff --git a/lib/index.js b/lib/index.js
index 7beb313..1a39592 100644
--- a/lib/index.js
+++ b/lib/index.js
@@ -175,7 +175,7 @@ RpcClient.callspec = {
   getMiningInfo: '',
   getNewAddress: '',
   getPeerInfo: '',
-  getRawMemPool: '',
+  getRawMemPool: 'bool',
   getRawTransaction: 'str int',
   getReceivedByAccount: 'str int',
   getReceivedByAddress: 'str int',