diff --git a/css/leptonChrome.css b/css/leptonChrome.css
index 555ff0d..b8dc386 100644
--- a/css/leptonChrome.css
+++ b/css/leptonChrome.css
@@ -3965,6 +3965,11 @@
     --tab-border-radius: 0 !important; /* Original: 4px */
   }
 }
+@media not -moz-pref("userChrome.rounding.square_tab") {
+  :root {
+    --tab-border-radius: 4px !important; /* Original: 4px */
+  }
+}
 @media -moz-pref("userChrome.rounding.square_button") {
   :root {
     --urlbar-icon-border-radius: 0 !important; /* Original: calc(var(--toolbarbutton-border-radius) - 1px); */
@@ -18458,6 +18463,11 @@
     --tab-border-radius: 0 !important; /* Original: 4px */
   }
 }
+@media not (-moz-bool-pref: "userChrome.rounding.square_tab") {
+  :root {
+    --tab-border-radius: 4px !important; /* Original: 4px */
+  }
+}
 @media (-moz-bool-pref: "userChrome.rounding.square_button") {
   :root {
     --urlbar-icon-border-radius: 0 !important; /* Original: calc(var(--toolbarbutton-border-radius) - 1px); */
diff --git a/css/leptonChromeESR.css b/css/leptonChromeESR.css
index 4cb28bf..e33e7e3 100644
--- a/css/leptonChromeESR.css
+++ b/css/leptonChromeESR.css
@@ -4286,6 +4286,11 @@
     --tab-border-radius: 0 !important; /* Original: 4px */
   }
 }
+@supports not -moz-bool-pref("userChrome.rounding.square_tab") {
+  :root {
+    --tab-border-radius: 4px !important; /* Original: 4px */
+  }
+}
 @supports -moz-bool-pref("userChrome.rounding.square_button") {
   :root {
     --urlbar-icon-border-radius: 0 !important; /* Original: calc(var(--toolbarbutton-border-radius) - 1px); */
diff --git a/src/rounding/_square.scss b/src/rounding/_square.scss
index 5722402..3140184 100644
--- a/src/rounding/_square.scss
+++ b/src/rounding/_square.scss
@@ -3,6 +3,11 @@
     --tab-border-radius: 0 !important; /* Original: 4px */
   }
 }
+@include NotOption("userChrome.rounding.square_tab") {
+  :root {
+    --tab-border-radius: 4px !important; /* Original: 4px */
+  }
+}
 @include Option("userChrome.rounding.square_button") {
   :root {
     --urlbar-icon-border-radius: 0 !important; /* Original: calc(var(--toolbarbutton-border-radius) - 1px); */