diff --git a/platform/firefox/vapi-background.js b/platform/firefox/vapi-background.js
index c14d4c3fd..37344a38e 100644
--- a/platform/firefox/vapi-background.js
+++ b/platform/firefox/vapi-background.js
@@ -1561,8 +1561,12 @@ vAPI.net.registerListeners = function() {
             for ( var tab of tabWatcher.tabs() ) {
                 var URI = tab.currentURI;
 
-                // Probably isn't the best method to identify the source tab
-                if ( URI.spec !== details.openerURL ) {
+                // Probably isn't the best method to identify the source tab.
+                // Apparently URI can be undefined under some circumstances: I
+                // believe this may have to do with those very temporary
+                // browser objects created when opening a new tab, i.e. related
+                // to https://github.com/gorhill/uBlock/issues/212
+                if ( URI && URI.spec !== details.openerURL ) {
                     continue;
                 }