diff --git a/content/base/src/nsNodeInfo.cpp b/content/base/src/nsNodeInfo.cpp
index f330b4b6d3d..2ef468f3528 100644
--- a/content/base/src/nsNodeInfo.cpp
+++ b/content/base/src/nsNodeInfo.cpp
@@ -66,8 +66,7 @@ static const size_t kNodeInfoPoolSizes[] = {
   sizeof(nsNodeInfo)
 };
 
-static const PRInt32 kNodeInfoPoolInitialSize = 
-  (NS_SIZE_IN_HEAP(sizeof(nsNodeInfo))) * 64;
+static const PRInt32 kNodeInfoPoolInitialSize = sizeof(nsNodeInfo) * 64;
 
 // static
 nsFixedSizeAllocator* nsNodeInfo::sNodeInfoPool = nsnull;
diff --git a/content/events/src/nsEventDispatcher.cpp b/content/events/src/nsEventDispatcher.cpp
index 8272aaabc9f..ab612503677 100644
--- a/content/events/src/nsEventDispatcher.cpp
+++ b/content/events/src/nsEventDispatcher.cpp
@@ -423,7 +423,7 @@ public:
         static const size_t kBucketSizes[] = { sizeof(nsEventTargetChainItem) };
         static const PRInt32 kNumBuckets = sizeof(kBucketSizes) / sizeof(size_t);
         static const PRInt32 kInitialPoolSize =
-          NS_SIZE_IN_HEAP(sizeof(nsEventTargetChainItem)) * NS_CHAIN_POOL_SIZE;
+          sizeof(nsEventTargetChainItem) * NS_CHAIN_POOL_SIZE;
         nsresult rv = sEtciPool->Init("EventTargetChainItem Pool", kBucketSizes,
                                       kNumBuckets, kInitialPoolSize);
         if (NS_FAILED(rv)) {
diff --git a/content/xbl/src/nsXBLPrototypeBinding.cpp b/content/xbl/src/nsXBLPrototypeBinding.cpp
index b11d2a2a6a6..72bc76b6200 100644
--- a/content/xbl/src/nsXBLPrototypeBinding.cpp
+++ b/content/xbl/src/nsXBLPrototypeBinding.cpp
@@ -293,9 +293,9 @@ static const size_t kAttrBucketSizes[] = {
 };
 
 static const PRInt32 kAttrNumBuckets = sizeof(kAttrBucketSizes)/sizeof(size_t);
-static const PRInt32 kAttrInitialSize = (NS_SIZE_IN_HEAP(sizeof(nsXBLAttributeEntry))) * kNumElements;
+static const PRInt32 kAttrInitialSize = sizeof(nsXBLAttributeEntry) * kNumElements;
 
-static const PRInt32 kInsInitialSize = (NS_SIZE_IN_HEAP(sizeof(nsXBLInsertionPointEntry))) * kNumElements;
+static const PRInt32 kInsInitialSize = sizeof(nsXBLInsertionPointEntry) * kNumElements;
 
 // Implementation /////////////////////////////////////////////////////////////////
 
diff --git a/content/xbl/src/nsXBLService.cpp b/content/xbl/src/nsXBLService.cpp
index ebe97a1d80f..9efd33ea448 100644
--- a/content/xbl/src/nsXBLService.cpp
+++ b/content/xbl/src/nsXBLService.cpp
@@ -227,7 +227,7 @@ static const size_t kBucketSizes[] = {
 
 static const PRInt32 kNumBuckets = sizeof(kBucketSizes)/sizeof(size_t);
 static const PRInt32 kNumElements = 64;
-static const PRInt32 kInitialSize = (NS_SIZE_IN_HEAP(sizeof(nsXBLBindingRequest))) * kNumElements;
+static const PRInt32 kInitialSize = sizeof(nsXBLBindingRequest) * kNumElements;
 
 nsIXBLService* nsXBLBindingRequest::gXBLService = nsnull;
 int nsXBLBindingRequest::gRefCnt = 0;
diff --git a/parser/htmlparser/src/nsDTDUtils.cpp b/parser/htmlparser/src/nsDTDUtils.cpp
index 5454e8c36a3..538a3fffc3d 100644
--- a/parser/htmlparser/src/nsDTDUtils.cpp
+++ b/parser/htmlparser/src/nsDTDUtils.cpp
@@ -794,7 +794,7 @@ void nsDTDContext::ReleaseGlobalObjects(void){
 
 static const size_t  kTokenBuckets[]       ={sizeof(CStartToken),sizeof(CAttributeToken),sizeof(CCommentToken),sizeof(CEndToken)};
 static const PRInt32 kNumTokenBuckets      = sizeof(kTokenBuckets) / sizeof(size_t);
-static const PRInt32 kInitialTokenPoolSize = NS_SIZE_IN_HEAP(sizeof(CToken)) * 200;
+static const PRInt32 kInitialTokenPoolSize = sizeof(CToken) * 200;
 
 /**
  * 
@@ -955,7 +955,7 @@ nsNodeAllocator::nsNodeAllocator():mSharedNodes(0){
 #else 
   static const size_t  kNodeBuckets[]       = { sizeof(nsCParserNode), sizeof(nsCParserStartNode) };
   static const PRInt32 kNumNodeBuckets      = sizeof(kNodeBuckets) / sizeof(size_t);
-  static const PRInt32 kInitialNodePoolSize = NS_SIZE_IN_HEAP(sizeof(nsCParserNode)) * 35; // optimal size based on space-trace data
+  static const PRInt32 kInitialNodePoolSize = sizeof(nsCParserNode) * 35; // optimal size based on space-trace data
 nsNodeAllocator::nsNodeAllocator() {
   mNodePool.Init("NodePool", kNodeBuckets, kNumNodeBuckets, kInitialNodePoolSize);
 #endif
diff --git a/xpcom/ds/nsFixedSizeAllocator.h b/xpcom/ds/nsFixedSizeAllocator.h
index 014d5795943..48b54bb39c2 100644
--- a/xpcom/ds/nsFixedSizeAllocator.h
+++ b/xpcom/ds/nsFixedSizeAllocator.h
@@ -96,8 +96,7 @@
 
       // This is the intial size of the allocator, in bytes. We'll
       // assume that we want to start with space for 1024 Foo objects.
-      static const PRInt32 kInitialPoolSize =
-        NS_SIZE_IN_HEAP(sizeof(Foo)) * 1024;
+      static const PRInt32 kInitialPoolSize = sizeof(Foo) * 1024;
 
       // Initialize (or re-initialize) the pool
       pool.Init("TheFooPool", kBucketSizes, kNumBuckets, kInitialPoolSize);
@@ -132,8 +131,6 @@
 #include "nsError.h"
 #include "plarena.h"
 
-#define NS_SIZE_IN_HEAP(_size) (_size)
-
 class nsFixedSizeAllocator
 {
 protected:
diff --git a/xpcom/threads/nsTimerImpl.cpp b/xpcom/threads/nsTimerImpl.cpp
index 6a5d673e16e..8a451c79973 100644
--- a/xpcom/threads/nsTimerImpl.cpp
+++ b/xpcom/threads/nsTimerImpl.cpp
@@ -561,7 +561,7 @@ void nsTimerEvent::Init()
   sAllocator = new TimerEventAllocator();
   static const size_t kBucketSizes[] = {sizeof(nsTimerEvent)};
   static const PRInt32 kNumBuckets = mozilla::ArrayLength(kBucketSizes);
-  static const PRInt32 kInitialPoolSize = 1024 * NS_SIZE_IN_HEAP(sizeof(nsTimerEvent));
+  static const PRInt32 kInitialPoolSize = 1024 * sizeof(nsTimerEvent);
   sAllocator->Init("TimerEventPool", kBucketSizes, kNumBuckets, kInitialPoolSize);
 }