diff --git a/README.markdown b/README.markdown
index 67681dd..de453cc 100644
--- a/README.markdown
+++ b/README.markdown
@@ -323,7 +323,7 @@ After copying and pasting code to do this several times I decided to package it
 
 DatabaseCleaner comes with safeguards against:
 
-* Running in production (checking for `ENV`, `RACK_ENV`, and `RAILS_ENV`)
+* Running in production (checking for `ENV`, `APP_ENV`, `RACK_ENV`, and `RAILS_ENV`)
 * Running against a remote database (checking for a `DATABASE_URL` that does not include `localhost`, `.local` or `127.0.0.1`)
 
 Both safeguards can be disabled separately as follows.
diff --git a/lib/database_cleaner/safeguard.rb b/lib/database_cleaner/safeguard.rb
index 5ca2703..fa1cb0e 100644
--- a/lib/database_cleaner/safeguard.rb
+++ b/lib/database_cleaner/safeguard.rb
@@ -72,7 +72,7 @@ module DatabaseCleaner
     end
 
     class Production
-      KEYS = %w(ENV RACK_ENV RAILS_ENV)
+      KEYS = %w(ENV APP_ENV RACK_ENV RAILS_ENV)
 
       def run
         raise Error::ProductionEnv.new(key) if !skip? && given?
diff --git a/spec/database_cleaner/safeguard_spec.rb b/spec/database_cleaner/safeguard_spec.rb
index 573ae2c..d757223 100644
--- a/spec/database_cleaner/safeguard_spec.rb
+++ b/spec/database_cleaner/safeguard_spec.rb
@@ -126,7 +126,7 @@ module DatabaseCleaner
     end
 
     describe 'ENV is set to production' do
-      %w(ENV RACK_ENV RAILS_ENV).each do |key|
+      %w(ENV APP_ENV RACK_ENV RAILS_ENV).each do |key|
         describe "on #{key}" do
           before { stub_const('ENV', key => "production") }