diff --git a/js/xpconnect/src/XPCJSRuntime.cpp b/js/xpconnect/src/XPCJSRuntime.cpp
index f72a2a261473..28b0b19e1f60 100644
--- a/js/xpconnect/src/XPCJSRuntime.cpp
+++ b/js/xpconnect/src/XPCJSRuntime.cpp
@@ -240,16 +240,11 @@ CompartmentDestroyedCallback(JSFreeOp *fop, JSCompartment *compartment)
     XPCJSRuntime* self = nsXPConnect::GetRuntimeInstance();
     if (!self)
         return;
-    XPCCompartmentSet &set = self->GetCompartmentSet();
 
     // Get the current compartment private into an AutoPtr (which will do the
     // cleanup for us), and null out the private (which may already be null).
     nsAutoPtr<CompartmentPrivate> priv(GetCompartmentPrivate(compartment));
     JS_SetCompartmentPrivate(compartment, nullptr);
-
-    if (set.has(compartment))
-        set.remove(compartment);
-    return;
 }
 
 nsresult
@@ -2421,8 +2416,6 @@ XPCJSRuntime::XPCJSRuntime(nsXPConnect* aXPConnect)
 
     mJSHolders.Init(512);
 
-    mCompartmentSet.init();
-
     // Install a JavaScript 'debugger' keyword handler in debug builds only
 #ifdef DEBUG
     if (!JS_GetGlobalDebugHooks(mJSRuntime)->debuggerHandler)
@@ -2466,7 +2459,6 @@ XPCJSRuntime::newXPCJSRuntime(nsXPConnect* aXPConnect)
         self->GetNativeScriptableSharedMap()    &&
         self->GetDyingWrappedNativeProtoMap()   &&
         self->GetMapLock()                      &&
-        self->GetCompartmentSet().initialized() &&
         self->mWatchdogThread) {
         return self;
     }
diff --git a/js/xpconnect/src/nsXPConnect.cpp b/js/xpconnect/src/nsXPConnect.cpp
index 5fa0b058903d..773f79b89457 100644
--- a/js/xpconnect/src/nsXPConnect.cpp
+++ b/js/xpconnect/src/nsXPConnect.cpp
@@ -1092,11 +1092,6 @@ CreateGlobalObject(JSContext *cx, JSClass *clasp, nsIPrincipal *principal)
     // The constructor automatically attaches the scope to the compartment private
     // of |global|.
     (void) new XPCWrappedNativeScope(cx, global);
-    JSCompartment *compartment = js::GetObjectCompartment(global);
-
-    XPCCompartmentSet& set = nsXPConnect::GetRuntimeInstance()->GetCompartmentSet();
-    if (!set.put(compartment))
-        return nullptr;
 
 #ifdef DEBUG
     // Verify that the right trace hook is called. Note that this doesn't
diff --git a/js/xpconnect/src/xpcprivate.h b/js/xpconnect/src/xpcprivate.h
index c827e8303dfa..8be33a12a5e7 100644
--- a/js/xpconnect/src/xpcprivate.h
+++ b/js/xpconnect/src/xpcprivate.h
@@ -267,12 +267,6 @@ extern const char XPC_SCRIPT_ERROR_CONTRACTID[];
 extern const char XPC_ID_CONTRACTID[];
 extern const char XPC_XPCONNECT_CONTRACTID[];
 
-typedef js::HashSet<JSCompartment *,
-                    js::DefaultHasher<JSCompartment *>,
-                    js::SystemAllocPolicy> XPCCompartmentSet;
-
-typedef XPCCompartmentSet::Range XPCCompartmentRange;
-
 /***************************************************************************/
 // Useful macros...
 
@@ -718,9 +712,6 @@ public:
     XPCWrappedNativeProtoMap* GetDetachedWrappedNativeProtoMap() const
         {return mDetachedWrappedNativeProtoMap;}
 
-    XPCCompartmentSet& GetCompartmentSet()
-        {return mCompartmentSet;}
-
     XPCLock* GetMapLock() const {return mMapLock;}
 
     JSBool OnJSContextNew(JSContext* cx);
@@ -958,7 +949,6 @@ private:
     XPCNativeScriptableSharedMap* mNativeScriptableSharedMap;
     XPCWrappedNativeProtoMap* mDyingWrappedNativeProtoMap;
     XPCWrappedNativeProtoMap* mDetachedWrappedNativeProtoMap;
-    XPCCompartmentSet        mCompartmentSet;
     XPCLock* mMapLock;
     PRThread* mThreadRunningGC;
     nsTArray<nsXPCWrappedJS*> mWrappedJSToReleaseArray;