diff --git a/mobile/app/mobile.js b/mobile/app/mobile.js
index 5acfd5abbdc..a49501bef81 100644
--- a/mobile/app/mobile.js
+++ b/mobile/app/mobile.js
@@ -46,6 +46,11 @@ pref("browser.tabs.warnOnClose", true);
 
 pref("toolkit.screen.lock", false);
 
+// From libpref/src/init/all.js, extended to allow a slightly wider zoom range.
+pref("zoom.minPercent", 20);
+pref("zoom.maxPercent", 400);
+pref("toolkit.zoomManager.zoomValues", ".2,.3,.5,.67,.8,.9,1,1.1,1.2,1.33,1.5,1.7,2,2.4,3,4");
+
 /* use custom widget for html:select */
 pref("ui.use_native_popup_windows", true);