diff --git a/flow-typed/mobx.js b/flow-typed/mobx.js
index ae76dd4eb..8a9835112 100644
--- a/flow-typed/mobx.js
+++ b/flow-typed/mobx.js
@@ -50,7 +50,7 @@ declare module 'mobx' {
   	forEach(callbackfn: (value: V, index: K, map: IMap<K, V>) => void, thisArg?: any): void;
   	get(key: K): V | any;
   	has(key: K): boolean;
-  	set(key: K, value?: V): this;
+  	set(key: K, value?: V): any;
     size: number;
   }
 
diff --git a/package.json b/package.json
index 13bafdd61..3320fbcde 100644
--- a/package.json
+++ b/package.json
@@ -51,7 +51,7 @@
     "browserify": "^12.0.1",
     "coveralls": "^2.11.4",
     "faucet": "0.0.1",
-    "flow-bin": "^0.36.0",
+    "flow-bin": "0.36.0",
     "istanbul": "^0.3.21",
     "iterall": "^1.0.2",
     "lodash.intersection": "^3.2.0",