diff --git a/testing/mozharness/configs/merge_day/aurora_to_beta.py b/testing/mozharness/configs/merge_day/aurora_to_beta.py
index e894cafae4d0..7038d97c96fd 100644
--- a/testing/mozharness/configs/merge_day/aurora_to_beta.py
+++ b/testing/mozharness/configs/merge_day/aurora_to_beta.py
@@ -48,6 +48,13 @@ config = {
         ("browser/config/mozconfigs/whitelist",
          "ac_add_options --with-branding=browser/branding/aurora",
          "ac_add_options --with-branding=browser/branding/nightly"),
+    ] + [
+        ("build/mozconfig.common",
+         "MOZ_REQUIRE_SIGNING=${MOZ_REQUIRE_SIGNING-0}",
+         "MOZ_REQUIRE_SIGNING=${MOZ_REQUIRE_SIGNING-1}"),
+        ("build/mozconfig.common",
+         "# Disable enforcing that add-ons are signed by the trusted root",
+         "# Enable enforcing that add-ons are signed by the trusted root")
     ],
 
     # Disallow sharing, since we want pristine .hg directories.