diff --git a/accessible/aom/AccessibleNode.cpp b/accessible/aom/AccessibleNode.cpp
index 4a3a23771a0f..2fb7583c8925 100644
--- a/accessible/aom/AccessibleNode.cpp
+++ b/accessible/aom/AccessibleNode.cpp
@@ -37,20 +37,6 @@ AccessibleNode::AccessibleNode(nsINode* aNode) : mDOMNode(aNode)
   }
 }
 
-bool
-AccessibleNode::IsAOMEnabled(JSContext* aCx, JSObject* /*unused*/)
-{
-  static bool sPrefCached = false;
-  static bool sPrefCacheValue = false;
-
-  if (!sPrefCached) {
-    sPrefCached = true;
-    Preferences::AddBoolVarCache(&sPrefCacheValue, "accessibility.AOM.enabled");
-  }
-
-  return nsContentUtils::IsSystemCaller(aCx) || sPrefCacheValue;
-}
-
 AccessibleNode::~AccessibleNode()
 {
 }
diff --git a/accessible/aom/AccessibleNode.h b/accessible/aom/AccessibleNode.h
index 8527e1a4cb0a..71fc4609528f 100644
--- a/accessible/aom/AccessibleNode.h
+++ b/accessible/aom/AccessibleNode.h
@@ -49,8 +49,6 @@ public:
 
   a11y::Accessible* Internal() const { return mIntl; }
 
-  static bool IsAOMEnabled(JSContext*, JSObject*);
-
 protected:
   AccessibleNode(const AccessibleNode& aCopy) = delete;
   AccessibleNode& operator=(const AccessibleNode& aCopy) = delete;
diff --git a/dom/webidl/AccessibleNode.webidl b/dom/webidl/AccessibleNode.webidl
index f4e132a3b58b..0a6d07eb3788 100644
--- a/dom/webidl/AccessibleNode.webidl
+++ b/dom/webidl/AccessibleNode.webidl
@@ -4,7 +4,7 @@
  * You can obtain one at http://mozilla.org/MPL/2.0/.
  */
 
-[Func="AccessibleNode::IsAOMEnabled"]
+[Pref="accessibility.AOM.enabled"]
 interface AccessibleNode {
   readonly attribute DOMString role;
   [Frozen, Cached, Pure]
diff --git a/dom/webidl/Node.webidl b/dom/webidl/Node.webidl
index d866685daef5..ac910435fc86 100644
--- a/dom/webidl/Node.webidl
+++ b/dom/webidl/Node.webidl
@@ -112,7 +112,7 @@ interface Node : EventTarget {
   DOMString generateXPath();
 
 #ifdef ACCESSIBILITY
-  [Func="AccessibleNode::IsAOMEnabled"]
+  [Pref="accessibility.AOM.enabled"]
   readonly attribute AccessibleNode? accessibleNode;
 #endif
 };