--- a/toolkit/modules/addons/WebRequest.jsm
+++ b/toolkit/modules/addons/WebRequest.jsm
@@ -500,20 +500,22 @@ HttpObserverManager = {
     let loadInfo = channel.loadInfo;
     let policyType = loadInfo ?
                      loadInfo.externalContentPolicyType :
                      Ci.nsIContentPolicy.TYPE_OTHER;
 
     let requestHeaderNames;
     let responseHeaderNames;
 
-    let includeStatus = kind === "headersReceived" ||
-                        kind === "onRedirect" ||
-                        kind === "onStart" ||
-                        kind === "onStop";
+    let includeStatus = (
+                          kind === "headersReceived" ||
+                          kind === "onRedirect" ||
+                          kind === "onStart" ||
+                          kind === "onStop"
+                        ) && channel instanceof Ci.nsIHttpChannel;
 
     let commonData = null;
     let uri = channel.URI;
     for (let [callback, opts] of listeners.entries()) {
       if (!this.shouldRunListener(policyType, uri, opts.filter)) {
         continue;
       }