diff --git a/dom/base/nsGlobalWindow.cpp b/dom/base/nsGlobalWindow.cpp
index 3a99ed8604d..0b9ac998111 100644
--- a/dom/base/nsGlobalWindow.cpp
+++ b/dom/base/nsGlobalWindow.cpp
@@ -584,6 +584,20 @@ DialogValueHolder::Get(nsIPrincipal* aSubject, nsIVariant** aResult)
   return NS_OK;
 }
 
+void
+DialogValueHolder::Get(JSContext* aCx, JS::Handle<JSObject*> aScope,
+                       nsIPrincipal* aSubject,
+                       JS::MutableHandle<JS::Value> aResult,
+                       mozilla::ErrorResult& aError)
+{
+  if (aSubject->Subsumes(mOrigin)) {
+    aError = nsContentUtils::XPConnect()->VariantToJS(aCx, aScope,
+                                                      mValue, aResult);
+  } else {
+    aResult.setUndefined();
+  }
+}
+
 namespace mozilla {
 namespace dom {
 extern uint64_t
diff --git a/dom/base/nsGlobalWindow.h b/dom/base/nsGlobalWindow.h
index a05668c857e..1952d4eb18c 100644
--- a/dom/base/nsGlobalWindow.h
+++ b/dom/base/nsGlobalWindow.h
@@ -267,15 +267,7 @@ public:
     , mValue(aValue) {}
   nsresult Get(nsIPrincipal* aSubject, nsIVariant** aResult);
   void Get(JSContext* aCx, JS::Handle<JSObject*> aScope, nsIPrincipal* aSubject,
-           JS::MutableHandle<JS::Value> aResult, mozilla::ErrorResult& aError)
-  {
-    if (aSubject->Subsumes(mOrigin)) {
-      aError = nsContentUtils::XPConnect()->VariantToJS(aCx, aScope,
-                                                        mValue, aResult);
-    } else {
-      aResult.setUndefined();
-    }
-  }
+           JS::MutableHandle<JS::Value> aResult, mozilla::ErrorResult& aError);
 private:
   virtual ~DialogValueHolder() {}