diff --git a/dom/xbl/nsXBLDocumentInfo.cpp b/dom/xbl/nsXBLDocumentInfo.cpp
index 0d55317119c..ed92cb3c265 100644
--- a/dom/xbl/nsXBLDocumentInfo.cpp
+++ b/dom/xbl/nsXBLDocumentInfo.cpp
@@ -566,7 +566,7 @@ void
 AssertInCompilationScope()
 {
   AutoJSContext cx;
-  MOZ_ASSERT(JS_GetClass(JS::CurrentGlobalOrNull(cx)) ==
-             &nsXBLDocGlobalObject::gSharedGlobalClass);
+  // Note - Inverting the order of these operands is a rooting hazard.
+  MOZ_ASSERT(xpc::GetCompilationScope() == JS::CurrentGlobalOrNull(cx));
 }
 #endif
diff --git a/dom/xbl/nsXBLProtoImpl.cpp b/dom/xbl/nsXBLProtoImpl.cpp
index df3fc28f2ef..33d82dc486e 100644
--- a/dom/xbl/nsXBLProtoImpl.cpp
+++ b/dom/xbl/nsXBLProtoImpl.cpp
@@ -201,7 +201,7 @@ nsXBLProtoImpl::CompilePrototypeMembers(nsXBLPrototypeBinding* aBinding)
   // bind the prototype to a real xbl instance, we'll clone the pre-compiled JS into the real instance's 
   // context.
   AutoSafeJSContext cx;
-  JS::Rooted<JSObject*> compilationGlobal(cx, aBinding->XBLDocumentInfo()->GetCompilationGlobal());
+  JS::Rooted<JSObject*> compilationGlobal(cx, xpc::GetCompilationScope());
   NS_ENSURE_TRUE(compilationGlobal, NS_ERROR_UNEXPECTED);
   JSAutoCompartment ac(cx, compilationGlobal);
 
diff --git a/dom/xbl/nsXBLPrototypeBinding.cpp b/dom/xbl/nsXBLPrototypeBinding.cpp
index e0bc83ccb56..100c4f43229 100644
--- a/dom/xbl/nsXBLPrototypeBinding.cpp
+++ b/dom/xbl/nsXBLPrototypeBinding.cpp
@@ -919,7 +919,7 @@ nsXBLPrototypeBinding::Read(nsIObjectInputStream* aStream,
   }
 
   AutoSafeJSContext cx;
-  JS::Rooted<JSObject*> compilationGlobal(cx, aDocInfo->GetCompilationGlobal());
+  JS::Rooted<JSObject*> compilationGlobal(cx, xpc::GetCompilationScope());
   NS_ENSURE_TRUE(compilationGlobal, NS_ERROR_UNEXPECTED);
   JSAutoCompartment ac(cx, compilationGlobal);
 
@@ -1072,7 +1072,7 @@ nsXBLPrototypeBinding::Write(nsIObjectOutputStream* aStream)
   // computed on demand.
 
   AutoSafeJSContext cx;
-  JS::Rooted<JSObject*> compilationGlobal(cx, mXBLDocInfoWeak->GetCompilationGlobal());
+  JS::Rooted<JSObject*> compilationGlobal(cx, xpc::GetCompilationScope());
   NS_ENSURE_TRUE(compilationGlobal, NS_ERROR_UNEXPECTED);
   JSAutoCompartment ac(cx, compilationGlobal);