diff --git a/Casks/emacs-app-nightly.rb b/Casks/emacs-app-nightly.rb
index b2832891..221bf0c6 100644
--- a/Casks/emacs-app-nightly.rb
+++ b/Casks/emacs-app-nightly.rb
@@ -14,7 +14,10 @@ cask 'emacs-app-nightly' do
     url 'https://github.com/jimeh/emacs-builds.git'
     strategy :git do |tags|
       tags.map do |tag|
-        tag.gsub(/^Emacs\.(\d{4}-\d{2}-\d{2}\.\w+\.master)$/i, '\\1')
+        m = /^Emacs\.(\d{4}-\d{2}-\d{2}\.\w+\.master)$/.match(tag)
+        next unless m
+
+        m[1]
       end.compact
     end
   end
@@ -22,6 +25,7 @@ cask 'emacs-app-nightly' do
   conflicts_with(
     cask: %w[
       emacs-app
+      emacs-app-good
       emacs
       emacs-nightly
       emacs-pretest
diff --git a/templates/emacs-app-nightly.rb.tpl b/templates/emacs-app-nightly.rb.tpl
index f59ffc2c..da26a78f 100644
--- a/templates/emacs-app-nightly.rb.tpl
+++ b/templates/emacs-app-nightly.rb.tpl
@@ -14,7 +14,10 @@ cask 'emacs-app-nightly' do
     url 'https://github.com/jimeh/emacs-builds.git'
     strategy :git do |tags|
       tags.map do |tag|
-        tag.gsub(/^Emacs\.(\d{4}-\d{2}-\d{2}\.\w+\.master)$/i, '\\1')
+        m = /^Emacs\.(\d{4}-\d{2}-\d{2}\.\w+\.master)$/.match(tag)
+        next unless m
+
+        m[1]
       end.compact
     end
   end
@@ -22,6 +25,7 @@ cask 'emacs-app-nightly' do
   conflicts_with(
     cask: %w[
       emacs-app
+      emacs-app-good
       emacs
       emacs-nightly
       emacs-pretest