diff --git a/dom/base/Selection.h b/dom/base/Selection.h
index 275ec54b893b..261e164c1b46 100644
--- a/dom/base/Selection.h
+++ b/dom/base/Selection.h
@@ -56,8 +56,9 @@ struct RangeData
 namespace mozilla {
 namespace dom {
 
-class Selection final : public nsISelectionPrivate,
+class Selection final : public nsISelection,
                         public nsWrapperCache,
+                        public nsISelectionPrivate,
                         public nsSupportsWeakReference
 {
 protected:
@@ -68,7 +69,7 @@ public:
   explicit Selection(nsFrameSelection *aList);
 
   NS_DECL_CYCLE_COLLECTING_ISUPPORTS
-  NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS_AMBIGUOUS(Selection, nsISelectionPrivate)
+  NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS_AMBIGUOUS(Selection, nsISelection)
   NS_DECL_NSISELECTION
   NS_DECL_NSISELECTIONPRIVATE
 
diff --git a/dom/base/nsISelectionPrivate.idl b/dom/base/nsISelectionPrivate.idl
index 00cdbd7dd140..2a22f48f1cad 100644
--- a/dom/base/nsISelectionPrivate.idl
+++ b/dom/base/nsISelectionPrivate.idl
@@ -28,7 +28,7 @@ native nsDirection(nsDirection);
 native ScrollAxis(nsIPresShell::ScrollAxis);
 
 [scriptable, builtinclass, uuid(0c9f4f74-ee7e-4fe9-be6b-0ba856368178)]
-interface nsISelectionPrivate : nsISelection
+interface nsISelectionPrivate : nsISupports
  {
     const short ENDOFPRECEDINGLINE=0;
     const short STARTOFNEXTLINE=1;