--- a/browser/base/content/nsContextMenu.js
+++ b/browser/base/content/nsContextMenu.js
@@ -1151,17 +1151,17 @@ nsContextMenu.prototype = {
                     loadingPrincipal: this.principal,
                     contentPolicyType: Ci.nsIContentPolicy.TYPE_SAVEAS_DOWNLOAD,
                     securityFlags: Ci.nsILoadInfo.SEC_ALLOW_CROSS_ORIGIN_DATA_INHERITS,
                   });
 
     if (linkDownload)
       channel.contentDispositionFilename = linkDownload;
     if (channel instanceof Ci.nsIPrivateBrowsingChannel) {
-      let docIsPrivate = PrivateBrowsingUtils.isBrowserPrivate(gBrowser.selectedBrowser);
+      let docIsPrivate = PrivateBrowsingUtils.isBrowserPrivate(this.browser);
       channel.setPrivate(docIsPrivate);
     }
     channel.notificationCallbacks = new callbacks();
 
     let flags = Ci.nsIChannel.LOAD_CALL_CONTENT_SNIFFERS;
 
     if (bypassCache)
       flags |= Ci.nsIRequest.LOAD_BYPASS_CACHE;