diff --git a/src/utils/ReactChildren.js b/src/utils/ReactChildren.js
index e470609bc74c8..2a6c43193e562 100644
--- a/src/utils/ReactChildren.js
+++ b/src/utils/ReactChildren.js
@@ -29,15 +29,15 @@ var threeArgumentPooler = PooledClass.threeArgumentPooler;
  * @param {?*} forEachContext Context to perform context with.
  */
 function ForEachBookKeeping(forEachFunction, forEachContext) {
-  this.forEachFunction = forEachFunction;
-  this.forEachContext = forEachContext;
+  this.func = forEachFunction;
+  this.context = forEachContext;
+  this.count = 0;
 }
 PooledClass.addPoolingTo(ForEachBookKeeping, twoArgumentPooler);
 
-function forEachSingleChild(traverseContext, child, name, i) {
-  var forEachBookKeeping = traverseContext;
-  forEachBookKeeping.forEachFunction.call(
-    forEachBookKeeping.forEachContext, child, i);
+function forEachSingleChild(traverseContext, child, name) {
+  var bookKeeping = traverseContext;
+  bookKeeping.func.call(bookKeeping.context, child, bookKeeping.count++);
 }
 
 /**
@@ -71,15 +71,16 @@ function forEachChildren(children, forEachFunc, forEachContext) {
  * @param {?*} mapContext Context to perform mapping with.
  */
 function MapBookKeeping(mapResult, mapFunction, mapContext) {
-  this.mapResult = mapResult;
-  this.mapFunction = mapFunction;
-  this.mapContext = mapContext;
+  this.result = mapResult;
+  this.func = mapFunction;
+  this.context = mapContext;
+  this.count = 0;
 }
 PooledClass.addPoolingTo(MapBookKeeping, threeArgumentPooler);
 
-function mapSingleChildIntoContext(traverseContext, child, name, i) {
-  var mapBookKeeping = traverseContext;
-  var mapResult = mapBookKeeping.mapResult;
+function mapSingleChildIntoContext(traverseContext, child, name) {
+  var bookKeeping = traverseContext;
+  var mapResult = bookKeeping.result;
 
   var keyUnique = (mapResult[name] === undefined);
   if (__DEV__) {
@@ -94,7 +95,7 @@ function mapSingleChildIntoContext(traverseContext, child, name, i) {
 
   if (keyUnique) {
     var mappedChild =
-      mapBookKeeping.mapFunction.call(mapBookKeeping.mapContext, child, i);
+      bookKeeping.func.call(bookKeeping.context, child, bookKeeping.count++);
     mapResult[name] = mappedChild;
   }
 }
@@ -125,7 +126,7 @@ function mapChildren(children, func, context) {
   return ReactFragment.create(mapResult);
 }
 
-function forEachSingleChildDummy(traverseContext, child, name, i) {
+function forEachSingleChildDummy(traverseContext, child, name) {
   return null;
 }
 
diff --git a/src/utils/__tests__/traverseAllChildren-test.js b/src/utils/__tests__/traverseAllChildren-test.js
index 4990fcad0a8f4..d8ed108595f2e 100644
--- a/src/utils/__tests__/traverseAllChildren-test.js
+++ b/src/utils/__tests__/traverseAllChildren-test.js
@@ -40,8 +40,7 @@ describe('traverseAllChildren', function() {
     expect(traverseFn).toHaveBeenCalledWith(
       traverseContext,
       simpleKid,
-      '.$simple',
-      0
+      '.$simple'
     );
     expect(traverseContext.length).toEqual(1);
   });
@@ -59,8 +58,7 @@ describe('traverseAllChildren', function() {
     expect(traverseFn).toHaveBeenCalledWith(
       traverseContext,
       simpleKid,
-      '.0',
-      0
+      '.0'
     );
     expect(traverseContext.length).toEqual(1);
   });
@@ -78,8 +76,7 @@ describe('traverseAllChildren', function() {
     expect(traverseFn).toHaveBeenCalledWith(
       traverseContext,
       simpleKid,
-      '.0',
-      0
+      '.0'
     );
     expect(traverseContext.length).toEqual(1);
   });
@@ -111,22 +108,19 @@ describe('traverseAllChildren', function() {
     expect(traverseFn).toHaveBeenCalledWith(
       traverseContext,
       zero,
-      '.$keyZero',
-      0
+      '.$keyZero'
     );
-    expect(traverseFn).toHaveBeenCalledWith(traverseContext, one, '.1', 1);
+    expect(traverseFn).toHaveBeenCalledWith(traverseContext, one, '.1');
     expect(traverseFn).toHaveBeenCalledWith(
       traverseContext,
       two,
-      '.$keyTwo',
-      2
+      '.$keyTwo'
     );
-    expect(traverseFn).toHaveBeenCalledWith(traverseContext, three, '.3', 3);
+    expect(traverseFn).toHaveBeenCalledWith(traverseContext, three, '.3');
     expect(traverseFn).toHaveBeenCalledWith(
       traverseContext,
       four,
-      '.$keyFour',
-      4
+      '.$keyFour'
     );
   });
 
@@ -161,31 +155,31 @@ describe('traverseAllChildren', function() {
     expect(traverseContext.length).toEqual(9);
 
     expect(traverseFn).toHaveBeenCalledWith(
-      traverseContext, div, '.$divNode', 0
+      traverseContext, div, '.$divNode'
     );
     expect(traverseFn).toHaveBeenCalledWith(
-      traverseContext, span, '.1:0:$span:$spanNode', 1
+      traverseContext, span, '.1:0:$span:$spanNode'
     );
     expect(traverseFn).toHaveBeenCalledWith(
-      traverseContext, a, '.2:$a:$aNode', 2
+      traverseContext, a, '.2:$a:$aNode'
     );
     expect(traverseFn).toHaveBeenCalledWith(
-      traverseContext, 'string', '.3', 3
+      traverseContext, 'string', '.3'
     );
     expect(traverseFn).toHaveBeenCalledWith(
-      traverseContext, 1234, '.4', 4
+      traverseContext, 1234, '.4'
     );
     expect(traverseFn).toHaveBeenCalledWith(
-      traverseContext, null, '.5', 5
+      traverseContext, null, '.5'
     );
     expect(traverseFn).toHaveBeenCalledWith(
-      traverseContext, null, '.6', 6
+      traverseContext, null, '.6'
     );
     expect(traverseFn).toHaveBeenCalledWith(
-      traverseContext, null, '.7', 7
+      traverseContext, null, '.7'
     );
     expect(traverseFn).toHaveBeenCalledWith(
-      traverseContext, null, '.8', 8
+      traverseContext, null, '.8'
     );
   });
 
@@ -225,39 +219,34 @@ describe('traverseAllChildren', function() {
     expect(traverseFn).toHaveBeenCalledWith(
       traverseContext,
       zero,
-      '.0:$firstHalfKey:0:$keyZero',
-      0
+      '.0:$firstHalfKey:0:$keyZero'
     );
 
     expect(traverseFn)
-      .toHaveBeenCalledWith(traverseContext, one, '.0:$firstHalfKey:0:1', 1);
+      .toHaveBeenCalledWith(traverseContext, one, '.0:$firstHalfKey:0:1');
 
     expect(traverseFn).toHaveBeenCalledWith(
       traverseContext,
       two,
-      '.0:$firstHalfKey:0:$keyTwo',
-      2
+      '.0:$firstHalfKey:0:$keyTwo'
     );
 
     expect(traverseFn).toHaveBeenCalledWith(
       traverseContext,
       three,
-      '.0:$secondHalfKey:0:0',
-      3
+      '.0:$secondHalfKey:0:0'
     );
 
     expect(traverseFn).toHaveBeenCalledWith(
       traverseContext,
       four,
-      '.0:$secondHalfKey:0:$keyFour',
-      4
+      '.0:$secondHalfKey:0:$keyFour'
     );
 
     expect(traverseFn).toHaveBeenCalledWith(
       traverseContext,
       five,
-      '.0:$keyFive:$keyFiveInner',
-      5
+      '.0:$keyFive:$keyFiveInner'
     );
   });
 
@@ -282,14 +271,12 @@ describe('traverseAllChildren', function() {
     expect(traverseFn).toHaveBeenCalledWith(
       traverseContext,
       zeroForceKey,
-      '.$keyZero',
-      0
+      '.$keyZero'
     );
     expect(traverseFn).toHaveBeenCalledWith(
       traverseContext,
       oneForceKey,
-      '.$keyOne',
-      1
+      '.$keyOne'
     );
   });
 
@@ -327,20 +314,17 @@ describe('traverseAllChildren', function() {
     expect(traverseFn).toHaveBeenCalledWith(
       traverseContext,
       traverseContext[0],
-      '.0',
-      0
+      '.0'
     );
     expect(traverseFn).toHaveBeenCalledWith(
       traverseContext,
       traverseContext[1],
-      '.1',
-      1
+      '.1'
     );
     expect(traverseFn).toHaveBeenCalledWith(
       traverseContext,
       traverseContext[2],
-      '.2',
-      2
+      '.2'
     );
   });
 
@@ -378,20 +362,17 @@ describe('traverseAllChildren', function() {
     expect(traverseFn).toHaveBeenCalledWith(
       traverseContext,
       traverseContext[0],
-      '.$#1',
-      0
+      '.$#1'
     );
     expect(traverseFn).toHaveBeenCalledWith(
       traverseContext,
       traverseContext[1],
-      '.$#2',
-      1
+      '.$#2'
     );
     expect(traverseFn).toHaveBeenCalledWith(
       traverseContext,
       traverseContext[2],
-      '.$#3',
-      2
+      '.$#3'
     );
   });
 
@@ -432,20 +413,17 @@ describe('traverseAllChildren', function() {
     expect(traverseFn).toHaveBeenCalledWith(
       traverseContext,
       traverseContext[0],
-      '.$#1:0',
-      0
+      '.$#1:0'
     );
     expect(traverseFn).toHaveBeenCalledWith(
       traverseContext,
       traverseContext[1],
-      '.$#2:0',
-      1
+      '.$#2:0'
     );
     expect(traverseFn).toHaveBeenCalledWith(
       traverseContext,
       traverseContext[2],
-      '.$#3:0',
-      2
+      '.$#3:0'
     );
 
     expect(console.error.argsForCall.length).toBe(1);
diff --git a/src/utils/traverseAllChildren.js b/src/utils/traverseAllChildren.js
index e547237a5a3ab..6c34832ed2e16 100644
--- a/src/utils/traverseAllChildren.js
+++ b/src/utils/traverseAllChildren.js
@@ -84,7 +84,6 @@ function wrapUserProvidedKey(key) {
 /**
  * @param {?*} children Children tree container.
  * @param {!string} nameSoFar Name of the key path so far.
- * @param {!number} indexSoFar Number of children encountered until this point.
  * @param {!function} callback Callback to invoke with each child found.
  * @param {?*} traverseContext Used to pass information throughout the traversal
  * process.
@@ -93,7 +92,6 @@ function wrapUserProvidedKey(key) {
 function traverseAllChildrenImpl(
   children,
   nameSoFar,
-  indexSoFar,
   callback,
   traverseContext
 ) {
@@ -113,13 +111,13 @@ function traverseAllChildrenImpl(
       children,
       // If it's the only child, treat the name as if it was wrapped in an array
       // so that it's consistent if the number of children grows.
-      nameSoFar === '' ? SEPARATOR + getComponentKey(children, 0) : nameSoFar,
-      indexSoFar
+      nameSoFar === '' ? SEPARATOR + getComponentKey(children, 0) : nameSoFar
     );
     return 1;
   }
 
-  var child, nextName, nextIndex;
+  var child;
+  var nextName;
   var subtreeCount = 0; // Count of children found in the current subtree.
 
   if (Array.isArray(children)) {
@@ -129,11 +127,9 @@ function traverseAllChildrenImpl(
         (nameSoFar !== '' ? nameSoFar + SUBSEPARATOR : SEPARATOR) +
         getComponentKey(child, i)
       );
-      nextIndex = indexSoFar + subtreeCount;
       subtreeCount += traverseAllChildrenImpl(
         child,
         nextName,
-        nextIndex,
         callback,
         traverseContext
       );
@@ -151,11 +147,9 @@ function traverseAllChildrenImpl(
             (nameSoFar !== '' ? nameSoFar + SUBSEPARATOR : SEPARATOR) +
             getComponentKey(child, ii++)
           );
-          nextIndex = indexSoFar + subtreeCount;
           subtreeCount += traverseAllChildrenImpl(
             child,
             nextName,
-            nextIndex,
             callback,
             traverseContext
           );
@@ -180,11 +174,9 @@ function traverseAllChildrenImpl(
               wrapUserProvidedKey(entry[0]) + SUBSEPARATOR +
               getComponentKey(child, 0)
             );
-            nextIndex = indexSoFar + subtreeCount;
             subtreeCount += traverseAllChildrenImpl(
               child,
               nextName,
-              nextIndex,
               callback,
               traverseContext
             );
@@ -206,11 +198,9 @@ function traverseAllChildrenImpl(
             wrapUserProvidedKey(key) + SUBSEPARATOR +
             getComponentKey(child, 0)
           );
-          nextIndex = indexSoFar + subtreeCount;
           subtreeCount += traverseAllChildrenImpl(
             child,
             nextName,
-            nextIndex,
             callback,
             traverseContext
           );
@@ -243,7 +233,7 @@ function traverseAllChildren(children, callback, traverseContext) {
     return 0;
   }
 
-  return traverseAllChildrenImpl(children, '', 0, callback, traverseContext);
+  return traverseAllChildrenImpl(children, '', callback, traverseContext);
 }
 
 module.exports = traverseAllChildren;