diff --git a/mosh_app/mosh_client.html b/mosh_app/mosh_client.html
index c63a626..694c470 100644
--- a/mosh_app/mosh_client.html
+++ b/mosh_app/mosh_client.html
@@ -99,6 +99,10 @@
               </select>
             </td>
           </tr>
+          <tr id="ssh-agent-id-row">
+            <td>SSH agent id:</td>
+            <td><input id="ssh-agent-id" type="text" placeholder="beknehfpfkghjoafdifaflglpjkojoco"></td>
+          </tr>
           <tr>
             <td>
               DNS settings:
diff --git a/mosh_app/mosh_client.js b/mosh_app/mosh_client.js
index 3111537..cbdb9f4 100644
--- a/mosh_app/mosh_client.js
+++ b/mosh_app/mosh_client.js
@@ -230,6 +230,8 @@ function onConnectClick(e) {
       break;
     }
   }
+  args['ssh-agent-id'] = form['ssh-agent-id'].value ||
+      form['ssh-agent-id'].placeholder;
 
   // Define an ID that should, usually, uniquely define a connection to a
   // server. This will preserve the window position across sessions. But still
diff --git a/mosh_app/mosh_window.js b/mosh_app/mosh_window.js
index 5269f34..d14ca4c 100644
--- a/mosh_app/mosh_window.js
+++ b/mosh_app/mosh_window.js
@@ -75,8 +75,7 @@ mosh.CommandInstance = function(argv) {
   this.agentPort_ = null;
 
   // App ID of an SSH agent.
-  // TODO: Make this a user setting.
-  this.agentAppID_ = 'beknehfpfkghjoafdifaflglpjkojoco';
+  this.agentAppID_ = argv.args['ssh-agent-id'];
 };
 
 mosh.CommandInstance.prototype.run = function() {