diff --git a/Gemfile b/Gemfile
index 001591e..ade405b 100644
--- a/Gemfile
+++ b/Gemfile
@@ -8,4 +8,4 @@ gem 'rake'
 gem 'mysql2'
 gem 'rspec'
 gem 'byebug'
-gem 'activerecord', '~> 4.2.0'
+gem 'activerecord', '~> 5.2.3'
diff --git a/lib/louisville/extensions/history.rb b/lib/louisville/extensions/history.rb
index 6afa098..12acc9e 100644
--- a/lib/louisville/extensions/history.rb
+++ b/lib/louisville/extensions/history.rb
@@ -27,8 +27,8 @@ def self.included(base)
           extend ::Louisville::Extensions::History::ClassMethods
 
           # If our slug has changed we should manage the history.
-          after_save :delete_matching_historical_slug,  :if => :louisville_slug_changed?
-          after_save :generate_historical_slug,         :if => :louisville_slug_changed?
+          after_save :delete_matching_historical_slug,  if: :louisville_slug_previously_changed?
+          after_save :generate_historical_slug,         if: :louisville_slug_previously_changed?
 
           before_destroy :destroy_historical_slugs!
         end
@@ -63,7 +63,7 @@ def delete_matching_historical_slug
 
       # Then we generate a new historical slug for the previous value (if there is one).
       def generate_historical_slug
-        previous_value = self.send("#{louisville_config[:column]}_was")
+        previous_value = self.previous_changes[louisville_config[:column]].try(:[], 0)
 
         return unless previous_value
 
diff --git a/lib/louisville/slugger.rb b/lib/louisville/slugger.rb
index e6dc2b8..70a8748 100644
--- a/lib/louisville/slugger.rb
+++ b/lib/louisville/slugger.rb
@@ -53,6 +53,9 @@ def louisville_slug_changed?
       self.send("#{louisville_config[:column]}_changed?")
     end
 
+    def louisville_slug_previously_changed?
+      self.send("#{louisville_config[:column]}_previously_changed?")
+    end
 
     def apply_louisville_slug
       value = extract_louisville_slug_value_from_field
diff --git a/lib/louisville/version.rb b/lib/louisville/version.rb
index 569ac77..639e55d 100644
--- a/lib/louisville/version.rb
+++ b/lib/louisville/version.rb
@@ -3,7 +3,7 @@ module VERSION
 
     MAJOR = 0
     MINOR = 0
-    PATCH = 4
+    PATCH = 6
     PRE = nil
 
     def self.to_s
diff --git a/spec/spec_helper.rb b/spec/spec_helper.rb
index be63482..e50618a 100644
--- a/spec/spec_helper.rb
+++ b/spec/spec_helper.rb
@@ -7,6 +7,7 @@
 
 require 'active_record'
 require 'louisville'
+require 'yaml'
 
 begin
   require 'byebug'