diff --git a/dom/base/nsDOMWindowUtils.cpp b/dom/base/nsDOMWindowUtils.cpp
index b33069fc5de2..76e66ddfe33d 100644
--- a/dom/base/nsDOMWindowUtils.cpp
+++ b/dom/base/nsDOMWindowUtils.cpp
@@ -2686,7 +2686,9 @@ nsDOMWindowUtils::ZoomToFocusedInput() {
   }
 
   uint32_t flags = layers::DISABLE_ZOOM_OUT;
-  if (!Preferences::GetBool("formhelper.autozoom")) {
+  if (!Preferences::GetBool("formhelper.autozoom") ||
+      Preferences::GetBool("formhelper.autozoom.force-disable.test-only",
+                           /* aFallback = */ false)) {
     flags |= layers::PAN_INTO_VIEW_ONLY;
   } else {
     flags |= layers::ONLY_ZOOM_TO_DEFAULT_SCALE;
diff --git a/layout/base/tests/mochitest.ini b/layout/base/tests/mochitest.ini
index 797303d587ec..fd7d1cf25a33 100644
--- a/layout/base/tests/mochitest.ini
+++ b/layout/base/tests/mochitest.ini
@@ -1,6 +1,7 @@
 [DEFAULT]
 prefs =
   plugin.load_flash_only=false
+  formhelper.autozoom.force-disable.test-only=true
 support-files =
   Ahem.ttf
   file_bug842853.html
diff --git a/modules/libpref/init/all.js b/modules/libpref/init/all.js
index 86b07a9cbaf0..b5944a4718b3 100644
--- a/modules/libpref/init/all.js
+++ b/modules/libpref/init/all.js
@@ -582,6 +582,8 @@ pref("apz.overscroll.stretch_factor", "0.35");
 
 pref("apz.zoom-to-focused-input.enabled", true);
 
+pref("formhelper.autozoom.force-disable.test-only", false);
+
 #ifdef XP_MACOSX
   // Whether to run in native HiDPI mode on machines with "Retina"/HiDPI
   // display.