diff --git a/packages/jest-haste-map/src/index.js b/packages/jest-haste-map/src/index.js
index 1dddb1e0f537..445e7ff0c879 100644
--- a/packages/jest-haste-map/src/index.js
+++ b/packages/jest-haste-map/src/index.js
@@ -37,7 +37,6 @@ import type {Mapper} from './types';
 import type {Path} from 'types/Config';
 import type {
   HasteMap as HasteMapObject,
-  FileData as HasteMapFileData,
   InternalHasteMap,
   ModuleMetaData,
   ModuleMapData,
@@ -361,7 +360,7 @@ class HasteMap extends EventEmitter {
    * 2. crawl the file system.
    */
   _buildFileMap(): Promise<{
-    deprecatedFiles: HasteMapFileData,
+    deprecatedFiles: Array<{moduleName: string, path: string}>,
     hasteMap: InternalHasteMap,
   }> {
     const read = this._options.resetCache ? this._createEmptyMap : this.read;
@@ -370,14 +369,15 @@ class HasteMap extends EventEmitter {
       .then(() => read.call(this))
       .catch(() => this._createEmptyMap())
       .then(cachedHasteMap => {
-        const cachedFiles = new Map(cachedHasteMap.files);
+        const cachedFiles = [];
+        for (const [relativeFilePath, fileMetadata] of cachedHasteMap.files) {
+          const moduleName = fileMetadata[H.ID];
+          cachedFiles.push({moduleName, path: relativeFilePath});
+        }
         return this._crawl(cachedHasteMap).then(hasteMap => {
-          const deprecatedFiles = new Map();
-          for (const [fileName, fileData] of cachedFiles) {
-            if (!hasteMap.files.has(fileName)) {
-              deprecatedFiles.set(fileName, fileData);
-            }
-          }
+          const deprecatedFiles = cachedFiles.filter(
+            file => !hasteMap.files.has(file.path),
+          );
           return {deprecatedFiles, hasteMap};
         });
       });
@@ -579,7 +579,7 @@ class HasteMap extends EventEmitter {
   }
 
   _buildHasteMap(data: {
-    deprecatedFiles: HasteMapFileData,
+    deprecatedFiles: Array<{moduleName: string, path: string}>,
     hasteMap: InternalHasteMap,
   }): Promise<InternalHasteMap> {
     const {deprecatedFiles, hasteMap} = data;
@@ -587,9 +587,9 @@ class HasteMap extends EventEmitter {
     const mocks = new Map();
     const promises = [];
 
-    for (const [filePath, fileData] of deprecatedFiles) {
-      const moduleName = fileData[H.ID];
-      this._recoverDuplicates(hasteMap, filePath, moduleName);
+    for (let i = 0; i < deprecatedFiles.length; ++i) {
+      const file = deprecatedFiles[i];
+      this._recoverDuplicates(hasteMap, file.path, file.moduleName);
     }
 
     for (const relativeFilePath of hasteMap.files.keys()) {