--- a/toolkit/components/extensions/ExtensionUtils.jsm
+++ b/toolkit/components/extensions/ExtensionUtils.jsm
@@ -1635,17 +1635,17 @@ class ProxyAPIImplementation extends Sch
   removeListener(listener) {
     let set = this.childApiManager.listeners.get(this.path);
     if (!set) {
       return;
     }
     set.remove(listener);
 
     if (set.size == 0) {
-      this.childApiManager.messageManager.sendAsyncMessage("Extension:RemoveListener", {
+      this.childApiManager.messageManager.sendAsyncMessage("API:RemoveListener", {
         childId: this.childApiManager.id,
         path: this.path,
       });
     }
   }
 
   hasListener(listener) {
     let set = this.childApiManager.listeners.get(this.path);