diff --git a/lib/utils/objects.js b/lib/utils/objects.js
index d046022e0..1b136c751 100644
--- a/lib/utils/objects.js
+++ b/lib/utils/objects.js
@@ -1,152 +1,145 @@
 // @flow
 
 import stableStringify from 'fast-json-stable-stringify';
 import invariant from 'invariant';
 import _isEqual from 'lodash/fp/isEqual.js';
 import _isPlainObject from 'lodash/fp/isPlainObject.js';
 import stringHash from 'string-hash';
 
 type ObjectMap<K, T> = { +[key: K]: T };
 type NestedObjectMap<K, T> = { +[key: K]: T | NestedObjectMap<K, T> };
 
 function findMaximumDepth(obj: Object): ?{ path: string, depth: number } {
   let longestPath = null;
   let longestDepth = null;
   for (const key in obj) {
     const value = obj[key];
     if (typeof value !== 'object' || !value) {
       if (!longestDepth) {
         longestPath = key;
         longestDepth = 1;
       }
       continue;
     }
     const childResult = findMaximumDepth(obj[key]);
     if (!childResult) {
       continue;
     }
     const { path, depth } = childResult;
     const ourDepth = depth + 1;
     if (longestDepth === null || ourDepth > longestDepth) {
       longestPath = `${key}.${path}`;
       longestDepth = ourDepth;
     }
   }
   if (!longestPath || !longestDepth) {
     return null;
   }
   return { path: longestPath, depth: longestDepth };
 }
 
 function values<K, T>(map: ObjectMap<K, T>): T[] {
   return Object.values
-    ? // https://github.com/facebook/flow/issues/2221
-      // $FlowFixMe - Object.values currently does not have good flow support
-      Object.values(map)
+    ? Object.values(map)
     : Object.keys(map).map((key: K): T => map[key]);
 }
 
-function keys<K, T>(map: ObjectMap<K, T>): K[] {
-  return Object.keys(map);
-}
-
 function entries<K: string, T>(map: ObjectMap<K, T>): [K, T][] {
-  // $FlowFixMe - flow treats the values as mixed, but we know that they are T
   return Object.entries(map);
 }
 
 function assignValueWithKey<K, T>(
   obj: NestedObjectMap<K, T>,
   key: K,
   value: T | NestedObjectMap<K, T>,
 ): NestedObjectMap<K, T> {
   return {
     ...obj,
     ...Object.fromEntries([[key, value]]),
   };
 }
 
 function hash(obj: ?Object): number {
   if (!obj) {
     return -1;
   }
   return stringHash(stableStringify(obj));
 }
 
 // This function doesn't look at the order of the hashes inside of the array
 // e.g `combineUnorderedHashes([1,2,3]) === combineUnorderedHashes([3,1,2])`
 // so it should only be used if the hashes include their ordering in them
 // somehow (e.g. `RawThreadInfo` contains `id`)
 function combineUnorderedHashes(hashes: $ReadOnlyArray<number>): number {
   return hashes.reduce((a, v) => a ^ v, 0);
 }
 
 // returns an object with properties from obj1 not included in obj2
 function deepDiff<K, T>(
   obj1: NestedObjectMap<K, T>,
   obj2: NestedObjectMap<K, T>,
 ): NestedObjectMap<K, T> {
   let diff: NestedObjectMap<K, T> = {};
-  keys(obj1).forEach((key: K) => {
+  Object.keys(obj1).forEach((key: K) => {
     if (_isEqual(obj1[key], obj2[key])) {
       return;
     }
 
     if (!_isPlainObject(obj1[key]) || !_isPlainObject(obj2[key])) {
       diff = assignValueWithKey(diff, key, obj1[key]);
       return;
     }
 
     const nestedObj1: ObjectMap<K, T> = (obj1[key]: any);
     const nestedObj2: ObjectMap<K, T> = (obj2[key]: any);
 
     const nestedDiff = deepDiff(nestedObj1, nestedObj2);
     if (Object.keys(nestedDiff).length > 0) {
       diff = assignValueWithKey(diff, key, nestedDiff);
     }
   });
   return diff;
 }
 
 function assertObjectsAreEqual<K, T>(
   processedObject: ObjectMap<K, T>,
   expectedObject: ObjectMap<K, T>,
   message: string,
-) {
+): void {
   if (_isEqual(processedObject)(expectedObject)) {
     return;
   }
   const dataProcessedButNotExpected = deepDiff(processedObject, expectedObject);
   const dataExpectedButNotProcessed = deepDiff(expectedObject, processedObject);
 
   throw new Error(
     `${message}: Objects should be equal.` +
       ` Data processed but not expected:` +
       ` ${JSON.stringify(dataProcessedButNotExpected)}` +
       ` Data expected but not processed:` +
       ` ${JSON.stringify(dataExpectedButNotProcessed)}`,
   );
 }
 
 function invertObjectToMap<K, V>(obj: { +[K]: V }): Map<V, K> {
   const invertedMap = new Map<V, K>();
   for (const key of Object.keys(obj)) {
     invariant(
       !invertedMap.has(obj[key]),
       `invertObjectToMap: obj[${key}] is already in invertedMap`,
     );
     invertedMap.set(obj[key], key);
   }
   return invertedMap;
 }
 
 export {
   findMaximumDepth,
   values,
   hash,
   combineUnorderedHashes,
   assertObjectsAreEqual,
   deepDiff,
   entries,
   invertObjectToMap,
 };