diff --git a/browser/components/tabbrowser/TabUnloader.sys.mjs b/browser/components/tabbrowser/TabUnloader.sys.mjs
index aefccef39f0b81176a5710a794e8a5e2650d6507..e073c65790df6d55e827a4f4596199f4f1a99a57 100644
--- a/browser/components/tabbrowser/TabUnloader.sys.mjs
+++ b/browser/components/tabbrowser/TabUnloader.sys.mjs
@@ -52,7 +52,7 @@ let CRITERIA_WEIGHT = 1;
  */
 let DefaultTabUnloaderMethods = {
   isNonDiscardable(tab, weight) {
-    if (tab.undiscardable || tab.selected) {
+    if (tab.undiscardable || tab.selected || tab.zenModeActive) {
       return weight;
     }