diff --git a/.github/workflows/_prepare.yml b/.github/workflows/_prepare.yml
index a2e7aa3..3fb8fda 100644
--- a/.github/workflows/_prepare.yml
+++ b/.github/workflows/_prepare.yml
@@ -5,8 +5,9 @@ on:
     inputs:
       builder_ref:
         description: Git ref to checkout of build-emacs-for-macos
-        required: true
+        required: false
         type: string
+        default: "v0.6.18"
     secrets:
       TAP_REPO_TOKEN:
         description: Personal Access Token for Homebrew Tap repo
diff --git a/.github/workflows/nightly-emacs-28.yml b/.github/workflows/nightly-emacs-28.yml
index 7e31a33..dadeb41 100644
--- a/.github/workflows/nightly-emacs-28.yml
+++ b/.github/workflows/nightly-emacs-28.yml
@@ -13,8 +13,6 @@ jobs:
   prepare:
     name: Prepare
     uses: jimeh/emacs-builds/.github/workflows/_prepare.yml@main
-    with:
-      builder_ref: v0.6.17
     secrets:
       TAP_REPO_TOKEN: ${{ secrets.TAP_REPO_TOKEN }}
 
diff --git a/.github/workflows/nightly-master.yml b/.github/workflows/nightly-master.yml
index 8ab4fcd..c146331 100644
--- a/.github/workflows/nightly-master.yml
+++ b/.github/workflows/nightly-master.yml
@@ -13,8 +13,6 @@ jobs:
   prepare:
     name: Prepare
     uses: jimeh/emacs-builds/.github/workflows/_prepare.yml@main
-    with:
-      builder_ref: v0.6.17
     secrets:
       TAP_REPO_TOKEN: ${{ secrets.TAP_REPO_TOKEN }}