diff --git a/devtools/shared/protocol.js b/devtools/shared/protocol.js
index 46158e4076e6..c1092cc5806a 100644
--- a/devtools/shared/protocol.js
+++ b/devtools/shared/protocol.js
@@ -926,6 +926,13 @@ Pool.prototype = extend(EventEmitter.prototype, {
 });
 exports.Pool = Pool;
 
+/**
+ * Keep track of which actorSpecs have been created. If a replica of a spec
+ * is created, it can be caught, and specs which inherit from other specs will
+ * not overwrite eachother.
+ */
+var actorSpecs = new WeakMap();
+
 /**
  * An actor in the actor tree.
  *
@@ -938,6 +945,7 @@ exports.Pool = Pool;
 var Actor = function(conn) {
   Pool.call(this, conn);
 
+  this._actorSpec = actorSpecs.get(Object.getPrototypeOf(this));
   // Forward events to the connection.
   if (this._actorSpec && this._actorSpec.events) {
     for (let [name, request] of this._actorSpec.events.entries()) {
@@ -1170,8 +1178,6 @@ var generateRequestHandlers = function(actorSpec, actorProto) {
     actorProto.requestTypes[spec.request.type] = handler;
   });
 
-  actorProto._actorSpec = actorSpec;
-
   return actorProto;
 };
 
@@ -1197,6 +1203,8 @@ var ActorClassWithSpec = function(actorSpec, actorProto) {
   };
   cls.prototype = extend(Actor.prototype, generateRequestHandlers(actorSpec, actorProto));
 
+  actorSpecs.set(cls.prototype, actorSpec);
+
   return cls;
 };
 exports.ActorClassWithSpec = ActorClassWithSpec;