diff --git a/History.rdoc b/History.rdoc
index 80da1ba..7f89d06 100644
--- a/History.rdoc
+++ b/History.rdoc
@@ -3,6 +3,7 @@
 === Changes
   * Rename `url_whitelist` to `url_allowlist`
   * Allowlist now supports regular expressions
+  * Fixed Ruby 2.7 deprecation warnings
 
 === Breaking changes
   * Failed checks against the allowlist now raise `UrlNotAllowed` rather than `NotWhitelistedUrl`
diff --git a/README.markdown b/README.markdown
index 3e18fc3..b1d89fb 100644
--- a/README.markdown
+++ b/README.markdown
@@ -137,7 +137,7 @@ So what is fastest out of `:deletion` and `:truncation`? Well, it depends on you
 
 Some people report much faster speeds with `:deletion` while others say `:truncation` is faster for them. The best approach therefore is it try all options on your test suite and see what is faster.
 
-If you are using ActiveRecord then take a look at the [additional options](#additional-activerecord-options-for-truncation) available for `:truncation`.
+If you are using ActiveRecord then take a look at the [additional options](https://github.com/DatabaseCleaner/database_cleaner-active_record#strategy-configuration-options) available for `:truncation`.
 
 Database Cleaner also includes a `null` strategy (that does no cleaning at all) which can be used with any ORM library.
 You can also explicitly use it by setting your strategy to `nil`.
@@ -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/cleaners.rb b/lib/database_cleaner/cleaners.rb
index 506ca35..20cbf5f 100644
--- a/lib/database_cleaner/cleaners.rb
+++ b/lib/database_cleaner/cleaners.rb
@@ -7,9 +7,9 @@ module DatabaseCleaner
     end
 
     # FIXME this method conflates creation with lookup... both a command and a query. yuck.
-    def [](orm, opts = {})
+    def [](orm, **opts)
       raise ArgumentError if orm.nil?
-      fetch([orm, opts]) { add_cleaner(orm, opts) }
+      fetch([orm, opts]) { add_cleaner(orm, **opts) }
     end 
 
     def strategy=(strategy)
@@ -37,8 +37,8 @@ module DatabaseCleaner
 
     private
 
-    def add_cleaner(orm, opts = {})
-      self[[orm, opts]] = Cleaner.new(orm, opts)
+    def add_cleaner(orm, **opts)
+      self[[orm, opts]] = Cleaner.new(orm, **opts)
     end
 
     def remove_duplicates
diff --git a/lib/database_cleaner/safeguard.rb b/lib/database_cleaner/safeguard.rb
index 91197ca..353d0a7 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 89d8656..c933c0e 100644
--- a/spec/database_cleaner/safeguard_spec.rb
+++ b/spec/database_cleaner/safeguard_spec.rb
@@ -157,7 +157,7 @@ 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") }