--- a/toolkit/xre/nsAppRunner.cpp
+++ b/toolkit/xre/nsAppRunner.cpp
@@ -1101,27 +1101,16 @@ nsXULAppInfo::GetDefaultUpdateChannel(ns
 NS_IMETHODIMP
 nsXULAppInfo::GetDistributionID(nsACString& aResult)
 {
   aResult.AssignLiteral(MOZ_DISTRIBUTION_ID);
   return NS_OK;
 }
 
 NS_IMETHODIMP
-nsXULAppInfo::GetIsOfficial(bool* aResult)
-{
-#ifdef MOZILLA_OFFICIAL
-  *aResult = true;
-#else
-  *aResult = false;
-#endif
-  return NS_OK;
-}
-
-NS_IMETHODIMP
 nsXULAppInfo::GetWindowsDLLBlocklistStatus(bool* aResult)
 {
 #if defined(HAS_DLL_BLOCKLIST)
   *aResult = DllBlocklist_CheckStatus();
 #else
   *aResult = false;
 #endif
   return NS_OK;

--- a/xpcom/system/nsIXULRuntime.idl
+++ b/xpcom/system/nsIXULRuntime.idl
@@ -191,18 +191,13 @@ interface nsIXULRuntime : nsISupports
   readonly attribute AUTF8String defaultUpdateChannel;
 
   /**
    * The distribution ID for this build (MOZ_DISTRIBUTION_ID).
    */
   readonly attribute AUTF8String distributionID;
 
   /**
-   * True if this is an official build (MOZILLA_OFFICIAL).
-   */
-  readonly attribute boolean isOfficial;
-
-  /**
    * True if Windows DLL blocklist initialized correctly. This is
    * primarily for automated testing purposes.
    */
   readonly attribute boolean windowsDLLBlocklistStatus;
 };