diff --git a/toolkit/components/extensions/ExtensionUtils.jsm b/toolkit/components/extensions/ExtensionUtils.jsm
index af70256a9715..2152b9d5c735 100644
--- a/toolkit/components/extensions/ExtensionUtils.jsm
+++ b/toolkit/components/extensions/ExtensionUtils.jsm
@@ -166,7 +166,7 @@ class BaseContext {
     this.onClose = new Set();
     this.checkedLastError = false;
     this._lastError = null;
-    this.contextId = ++gContextId;
+    this.contextId = `${++gContextId}-${Services.appinfo.uniqueProcessID}`;
     this.unloaded = false;
     this.extensionId = extensionId;
     this.jsonSandbox = null;
@@ -1334,8 +1334,7 @@ Messenger.prototype = {
   },
 
   connect(messageManager, name, recipient) {
-    // TODO(robwu): Use a process ID instead of the process type. bugzil.la/1287626
-    let portId = `${gNextPortId++}-${Services.appinfo.processType}`;
+    let portId = `${gNextPortId++}-${Services.appinfo.uniqueProcessID}`;
     let port = new Port(this.context, messageManager, name, portId, null);
     let msg = {name, portId};
     this._sendMessage(messageManager, "Extension:Connect", msg, recipient)
diff --git a/toolkit/components/extensions/MessageChannel.jsm b/toolkit/components/extensions/MessageChannel.jsm
index f36566e4a85e..106d8c0294f9 100644
--- a/toolkit/components/extensions/MessageChannel.jsm
+++ b/toolkit/components/extensions/MessageChannel.jsm
@@ -497,7 +497,7 @@ this.MessageChannel = {
     let recipient = options.recipient || {};
     let responseType = options.responseType || this.RESPONSE_SINGLE;
 
-    let channelId = gChannelId++;
+    let channelId = `${gChannelId++}-${Services.appinfo.uniqueProcessID}`;
     let message = {messageName, channelId, sender, recipient, data, responseType};
 
     let deferred = PromiseUtils.defer();