diff --git a/packager/src/node-haste/lib/getInverseDependencies.js b/packager/src/node-haste/lib/getInverseDependencies.js
index d2aa7517b7a..6ff90334f87 100644
--- a/packager/src/node-haste/lib/getInverseDependencies.js
+++ b/packager/src/node-haste/lib/getInverseDependencies.js
@@ -5,17 +5,27 @@
  * This source code is licensed under the BSD-style license found in the
  * LICENSE file in the root directory of this source tree. An additional grant
  * of patent rights can be found in the PATENTS file in the same directory.
+ *
+ * @flow
+ * @format
  */
+
 'use strict';
 
-function resolveModuleRequires(resolutionResponse, module) {
+import type ResolutionResponse from '../DependencyGraph/ResolutionResponse';
+
+function resolveModuleRequires<TModule: {hash(): string}, TOptions>(
+  resolutionResponse: ResolutionResponse<TModule, TOptions>,
+  module: TModule,
+) {
   const pairs = resolutionResponse.getResolvedDependencyPairs(module);
-  return pairs
-    ? pairs.map(([, dependencyModule]) => dependencyModule)
-    : [];
+  return pairs ? pairs.map(([, dependencyModule]) => dependencyModule) : [];
 }
 
-function getModuleDependents(cache, module) {
+function getModuleDependents<TModule>(
+  cache: Map<TModule, Set<TModule>>,
+  module: TModule,
+): Set<TModule> {
   let dependents = cache.get(module);
   if (!dependents) {
     dependents = new Set();
@@ -27,7 +37,9 @@ function getModuleDependents(cache, module) {
 /**
  * Returns an object that indicates in which module each module is required.
  */
-function getInverseDependencies(resolutionResponse) {
+function getInverseDependencies<TModule: {hash(): string}, TOptions>(
+  resolutionResponse: ResolutionResponse<TModule, TOptions>,
+): Map<TModule, Set<TModule>> {
   const cache = new Map();
 
   resolutionResponse.dependencies.forEach(module => {