diff --git a/testing/mozharness/configs/merge_day/beta_to_release.py b/testing/mozharness/configs/merge_day/beta_to_release.py
index fe26b241f480..8b91eb4439d4 100644
--- a/testing/mozharness/configs/merge_day/beta_to_release.py
+++ b/testing/mozharness/configs/merge_day/beta_to_release.py
@@ -15,8 +15,7 @@ config = {
         ("{}{}".format(d, f),
         "ac_add_options --with-branding=mobile/android/branding/beta",
         "ac_add_options --with-branding=mobile/android/branding/official")
-        # TODO Bug 1389420: Rename api-15 into api-16 after Firefox 57 made Beta
-        for d in ["mobile/android/config/mozconfigs/android-api-15/",
+        for d in ["mobile/android/config/mozconfigs/android-api-16/",
                   "mobile/android/config/mozconfigs/android-x86/",
                   "mobile/android/config/mozconfigs/android-aarch64/"]
         for f in ["debug", "nightly", "l10n-nightly"]
@@ -24,8 +23,7 @@ config = {
         # File, from, to
         (f, "ac_add_options --with-l10n-base=../../mozilla-beta",
         "ac_add_options --with-l10n-base=../../mozilla-release")
-        # TODO Bug 1389420: Rename api-15 into api-16 after Firefox 57 made Beta
-        for f in ["mobile/android/config/mozconfigs/android-api-15/l10n-nightly",
+        for f in ["mobile/android/config/mozconfigs/android-api-16/l10n-nightly",
                   "mobile/android/config/mozconfigs/android-x86/l10n-nightly",
                   "mobile/android/config/mozconfigs/android-aarch64/l10n-nightly"]
     ] + [