diff --git a/userChrome.css b/userChrome.css
index 60cc51c..4492c32 100644
--- a/userChrome.css
+++ b/userChrome.css
@@ -1705,6 +1705,7 @@
     */
     --tabs-navbar-shadow-size: -1px; /* Original: 1px */
     --tabs-navbar-original-shadow-size: 1px;
+    --tab-corner-rounding: 4px; /* Hardcorded */
 
     /* Size */
     -moz-box-align: stretch !important;