diff --git a/browser/components/tabbrowser/TabUnloader.sys.mjs b/browser/components/tabbrowser/TabUnloader.sys.mjs
index 44846cc902fd3fc17d12be38ac9abccb47a12f23..c715c7cf47486066b3fd6f92bf78bc8a720759bc 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;
     }