diff --git a/rootfs/defaults/prefs.js b/rootfs/defaults/prefs.js
index 442c540..c91c032 100644
--- a/rootfs/defaults/prefs.js
+++ b/rootfs/defaults/prefs.js
@@ -1,2 +1,4 @@
 // Disable the privacy notice page.
 user_pref("toolkit.telemetry.reportingpolicy.firstRun", false);
+// Prevent closing Firefox when closing the last tab.
+user_pref("browser.tabs.closeWindowWithLastTab", false);