--- a/layout/generic/nsFloatManager.cpp
+++ b/layout/generic/nsFloatManager.cpp
@@ -37,17 +37,16 @@
  * ***** END LICENSE BLOCK ***** */
 
 /* class that manages rules for positioning floats */
 
 #include "nsFloatManager.h"
 #include "nsIPresShell.h"
 #include "nsMemory.h"
 #include "nsHTMLReflowState.h"
-#include "nsHashSets.h"
 #include "nsBlockDebugFlags.h"
 #include "nsContentErrors.h"
 
 using namespace mozilla;
 
 PRInt32 nsFloatManager::sCachedFloatManagerCount = 0;
 void* nsFloatManager::sCachedFloatManagers[NS_FLOAT_MANAGER_CACHE_SIZE];
 
@@ -363,21 +362,21 @@ nsFloatManager::RemoveTrailingRegions(ns
 {
   if (!aFrameList) {
     return NS_OK;
   }
   // This could be a good bit simpler if we could guarantee that the
   // floats given were at the end of our list, so we could just search
   // for the head of aFrameList.  (But we can't;
   // layout/reftests/bugs/421710-1.html crashes.)
-  nsVoidHashSet frameSet;
+  nsTHashtable<nsPtrHashKey<nsIFrame> > frameSet;
 
   frameSet.Init(1);
   for (nsIFrame* f = aFrameList; f; f = f->GetNextSibling()) {
-    frameSet.Put(f);
+    frameSet.PutEntry(f);
   }
 
   PRUint32 newLength = mFloats.Length();
   while (newLength > 0) {
     if (!frameSet.Contains(mFloats[newLength - 1].mFrame)) {
       break;
     }
     --newLength;