diff --git a/dom/public/nsIScriptContext.h b/dom/public/nsIScriptContext.h
index acd02591472c..651d58493997 100644
--- a/dom/public/nsIScriptContext.h
+++ b/dom/public/nsIScriptContext.h
@@ -41,6 +41,8 @@ class nsIScriptNameSpaceManager;
  */
 class nsIScriptContext : public nsISupports {
 public:
+  static const nsIID& IID() { static nsIID iid = NS_ISCRIPTCONTEXT_IID; return iid; }
+
   /**
    * Execute a script.
    *
diff --git a/dom/public/nsIScriptContextOwner.h b/dom/public/nsIScriptContextOwner.h
index 5187954596b4..7d63264af412 100644
--- a/dom/public/nsIScriptContextOwner.h
+++ b/dom/public/nsIScriptContextOwner.h
@@ -38,6 +38,8 @@ class nsIScriptContext;
 
 class nsIScriptContextOwner : public nsISupports {
 public:
+  static const nsIID& IID() { static nsIID iid = NS_ISCRIPTCONTEXTOWNER_IID; return iid; }
+
   /**
    * Returns a script context. The assumption is that the
    * script context has an associated script global object and