diff --git a/system-addon/lib/ActivityStreamMessageChannel.jsm b/system-addon/lib/ActivityStreamMessageChannel.jsm
index 6b44369ffe..081e0723e2 100644
--- a/system-addon/lib/ActivityStreamMessageChannel.jsm
+++ b/system-addon/lib/ActivityStreamMessageChannel.jsm
@@ -133,6 +133,13 @@ this.ActivityStreamMessageChannel = class ActivityStreamMessageChannel {
     this.channel.addMessageListener("RemotePage:Load", this.onNewTabLoad);
     this.channel.addMessageListener("RemotePage:Unload", this.onNewTabUnload);
     this.channel.addMessageListener(this.incomingMessageName, this.onMessage);
+
+    // Some pages might have already loaded, so we won't get the usual message
+    for (const {loaded, portID} of this.channel.messagePorts) {
+      if (loaded) {
+        this.onNewTabLoad({target: {portID}});
+      }
+    }
   }
 
   /**
diff --git a/system-addon/test/unit/lib/ActivityStreamMessageChannel.test.js b/system-addon/test/unit/lib/ActivityStreamMessageChannel.test.js
index da6e068469..5b2ee79313 100644
--- a/system-addon/test/unit/lib/ActivityStreamMessageChannel.test.js
+++ b/system-addon/test/unit/lib/ActivityStreamMessageChannel.test.js
@@ -9,10 +9,12 @@ describe("ActivityStreamMessageChannel", () => {
   let globals;
   let dispatch;
   let mm;
+  let RPmessagePorts;
   beforeEach(() => {
+    RPmessagePorts = [];
     function RP(url, isFromAboutNewTab = false) {
       this.url = url;
-      this.messagePorts = [];
+      this.messagePorts = RPmessagePorts;
       this.addMessageListener = globals.sandbox.spy();
       this.removeMessageListener = globals.sandbox.spy();
       this.sendAsyncMessage = globals.sandbox.spy();
@@ -78,6 +80,14 @@ describe("ActivityStreamMessageChannel", () => {
         mm.createChannel();
         assert.notCalled(global.AboutNewTab.override);
       });
+      it("should simluate load for loaded ports", () => {
+        sinon.stub(mm, "onActionFromContent");
+        RPmessagePorts.push({loaded: true, portID: "foo"});
+
+        mm.createChannel();
+
+        assert.calledWith(mm.onActionFromContent, {type: at.NEW_TAB_LOAD}, "foo");
+      });
     });
     describe("#destroyChannel", () => {
       let channel;