diff --git a/browser/devtools/webide/content/monitor.js b/browser/devtools/webide/content/monitor.js
index b2ee98849495..8c6562899fa0 100644
--- a/browser/devtools/webide/content/monitor.js
+++ b/browser/devtools/webide/content/monitor.js
@@ -295,7 +295,6 @@ function MonitorClient(client, form) {
 MonitorClient.prototype.destroy = function () {
   this.client.unregisterClient(this);
 }
-MonitorClient.prototype.detach = function () {}
 MonitorClient.prototype.start = function () {
   this.client.request({
     to: this.actor,
diff --git a/toolkit/devtools/client/dbg-client.jsm b/toolkit/devtools/client/dbg-client.jsm
index a5ec414fa17d..1b31d3020847 100644
--- a/toolkit/devtools/client/dbg-client.jsm
+++ b/toolkit/devtools/client/dbg-client.jsm
@@ -420,7 +420,11 @@ DebuggerClient.prototype = {
         this._transport = null;
         return;
       }
-      client.detach(detachClients);
+      if (client.detach) {
+        client.detach(detachClients);
+        return;
+      }
+      detachClients();
     };
     detachClients();
   },
@@ -1008,13 +1012,9 @@ DebuggerClient.prototype = {
     }
     if (client.events.length > 0 && typeof(client.emit) != "function") {
       throw new Error("DebuggerServer.registerClient expects " +
-                      "client instances with non-empty `events` array to" +
+                      "a client instance with non-empty `events` array to" +
                       "have an `emit` function.");
     }
-    if (typeof(client.detach) != "function") {
-      throw new Error("DebuggerServer.registerClient expects " +
-                      "a client instance with a `detach` function.");
-    }
     if (this._clients.has(actorID)) {
       throw new Error("DebuggerServer.registerClient already registered " +
                       "a client for this actor.");
diff --git a/toolkit/devtools/server/tests/unit/test_monitor_actor.js b/toolkit/devtools/server/tests/unit/test_monitor_actor.js
index f15aa31f66d4..817bcd58658c 100644
--- a/toolkit/devtools/server/tests/unit/test_monitor_actor.js
+++ b/toolkit/devtools/server/tests/unit/test_monitor_actor.js
@@ -27,7 +27,6 @@ function run_test()
   MonitorClient.prototype.destroy = function () {
     client.unregisterClient(this);
   }
-  MonitorClient.prototype.detach = function () {}
   MonitorClient.prototype.start = function (callback) {
     this.client.request({
       to: this.actor,