diff --git a/dom/xbl/nsXBLBinding.cpp b/dom/xbl/nsXBLBinding.cpp
index e662646de4f5..a77fade6fd73 100644
--- a/dom/xbl/nsXBLBinding.cpp
+++ b/dom/xbl/nsXBLBinding.cpp
@@ -121,8 +121,7 @@ nsXBLJSClass::Destroy()
                "referenced nsXBLJSClass is on LRU list already!?");
 
   if (nsXBLService::gClassTable) {
-    nsCStringKey key(mKey);
-    (nsXBLService::gClassTable)->Remove(&key);
+    nsXBLService::gClassTable->Remove(mKey);
     mKey.Truncate();
   }
 
@@ -141,14 +140,7 @@ nsXBLJSClass::Destroy()
 nsXBLJSClass*
 nsXBLService::getClass(const nsCString& k)
 {
-  nsCStringKey key(k);
-  return getClass(&key);
-}
-
-nsXBLJSClass*
-nsXBLService::getClass(nsCStringKey *k)
-{
-  return static_cast<nsXBLJSClass*>(nsXBLService::gClassTable->Get(k));
+  return nsXBLService::gClassTable->Get(k);
 }
 
 // Implementation /////////////////////////////////////////////////////////////////
@@ -995,9 +987,8 @@ nsXBLBinding::DoInitJSClass(JSContext *cx, JS::Handle<JSObject*> global,
     // We need to initialize the class.
     *aNew = true;
 
-    nsCStringKey key(xblKey);
     if (!c) {
-      c = nsXBLService::getClass(&key);
+      c = nsXBLService::getClass(xblKey);
     }
     if (c) {
       // If c is on the LRU list, remove it now!
@@ -1015,8 +1006,7 @@ nsXBLBinding::DoInitJSClass(JSContext *cx, JS::Handle<JSObject*> global,
         nsXBLService::gClassLRUListLength--;
 
         // Remove any mapping from the old name to the class struct.
-        nsCStringKey oldKey(c->Key());
-        (nsXBLService::gClassTable)->Remove(&oldKey);
+        nsXBLService::gClassTable->Remove(c->Key());
 
         // Change the class name and we're done.
         nsMemory::Free((void*) c->name);
@@ -1025,7 +1015,7 @@ nsXBLBinding::DoInitJSClass(JSContext *cx, JS::Handle<JSObject*> global,
       }
 
       // Add c to our table.
-      (nsXBLService::gClassTable)->Put(&key, (void*)c);
+      nsXBLService::gClassTable->Put(xblKey, c);
     }
 
     // The prototype holds a strong reference to its class struct.
@@ -1046,7 +1036,7 @@ nsXBLBinding::DoInitJSClass(JSContext *cx, JS::Handle<JSObject*> global,
       // This will happen if we're OOM or if the security manager
       // denies defining the new class...
 
-      (nsXBLService::gClassTable)->Remove(&key);
+      nsXBLService::gClassTable->Remove(xblKey);
 
       c->Drop();
 
diff --git a/dom/xbl/nsXBLService.cpp b/dom/xbl/nsXBLService.cpp
index 5dcdd9113984..8c42e533f687 100644
--- a/dom/xbl/nsXBLService.cpp
+++ b/dom/xbl/nsXBLService.cpp
@@ -368,7 +368,7 @@ nsXBLStreamListener::HandleEvent(nsIDOMEvent* aEvent)
 // Static member variable initialization
 bool nsXBLService::gAllowDataURIs = false;
 
-nsHashtable* nsXBLService::gClassTable = nullptr;
+nsXBLService::ClassTable* nsXBLService::gClassTable = nullptr;
 
 LinkedList<nsXBLJSClass>* nsXBLService::gClassLRUList = nullptr;
 uint32_t nsXBLService::gClassLRUListLength = 0;
@@ -393,7 +393,7 @@ nsXBLService::Init()
 // Constructors/Destructors
 nsXBLService::nsXBLService(void)
 {
-  gClassTable = new nsHashtable();
+  gClassTable = new ClassTable();
   gClassLRUList = new LinkedList<nsXBLJSClass>();
 
   Preferences::AddBoolVarCache(&gAllowDataURIs, "layout.debug.enable_data_xbl");
diff --git a/dom/xbl/nsXBLService.h b/dom/xbl/nsXBLService.h
index 637faac336e8..b7d0dab9db77 100644
--- a/dom/xbl/nsXBLService.h
+++ b/dom/xbl/nsXBLService.h
@@ -14,8 +14,9 @@
 #include "nsWeakReference.h"
 #include "js/Class.h"           // nsXBLJSClass derives from JSClass
 #include "nsTArray.h"
+#include "nsDataHashtable.h"
+#include "nsHashKeys.h"
 
-class nsCStringKey;
 class nsXBLBinding;
 class nsXBLDocumentInfo;
 class nsXBLJSClass;
@@ -24,7 +25,6 @@ class nsIDocument;
 class nsString;
 class nsIURI;
 class nsIPrincipal;
-class nsHashtable;
 
 namespace mozilla {
 namespace dom {
@@ -123,7 +123,8 @@ protected:
 public:
   static bool gDisableChromeCache;
 
-  static nsHashtable* gClassTable;           // A table of nsXBLJSClass objects.
+  typedef nsDataHashtable<nsCStringHashKey, nsXBLJSClass*> ClassTable;
+  static ClassTable* gClassTable;           // A table of nsXBLJSClass objects.
 
   static mozilla::LinkedList<nsXBLJSClass>* gClassLRUList;
                                              // LRU list of cached classes.
@@ -135,7 +136,6 @@ public:
 
   // Look up the class by key in gClassTable.
   static nsXBLJSClass *getClass(const nsCString &key);
-  static nsXBLJSClass *getClass(nsCStringKey *key);
 };
 
 class nsXBLJSClass : public mozilla::LinkedListElement<nsXBLJSClass>