diff --git a/lib/pact/shared/active_support_support.rb b/lib/pact/shared/active_support_support.rb
index 0f693ef..2e4826b 100644
--- a/lib/pact/shared/active_support_support.rb
+++ b/lib/pact/shared/active_support_support.rb
@@ -2,22 +2,28 @@
 
 module Pact
   module ActiveSupportSupport
-
     extend self
 
     def fix_all_the_things thing
-      if thing.is_a?(Regexp)
-        fix_regexp(thing)
-      elsif thing.is_a?(Array)
-        thing.each{ | it | fix_all_the_things it }
-      elsif thing.is_a?(Hash)
-          thing.values.each{ | it | fix_all_the_things it }
-      elsif thing.class.name.start_with?("Pact")
-        thing.instance_variables.collect{ | iv_name | thing.instance_variable_get(iv_name)}.each do | iv |
-          fix_all_the_things iv
+      if defined?(ActiveSupport)
+        if thing.is_a?(Regexp)
+          fix_regexp(thing)
+        elsif thing.is_a?(Array)
+          thing.collect{ | it | fix_all_the_things it }
+        elsif thing.is_a?(Hash)
+          thing.each_with_object({}) { | (k, v), new_hash | new_hash[k] = fix_all_the_things(v) }
+        elsif thing.is_a?(Pact::Term)
+          # matcher Regexp is fixed in its own as_json method
+          thing
+        elsif thing.class.name.start_with?("Pact")
+          warn_about_regexp(thing)
+          thing
+        else
+          thing
         end
+      else
+        thing
       end
-      thing
     end
 
     # ActiveSupport JSON overwrites (i.e. TRAMPLES) the json methods of the Regexp class directly
@@ -27,10 +33,7 @@ def fix_all_the_things thing
     # original as_json to the Regexp instances in the ConsumerContract before we write them to the
     # pact file. If anyone can find a better way, please submit a pull request ASAP!
     def fix_regexp regexp
-      def regexp.as_json options = {}
-        {:json_class => 'Regexp', "o" => self.options, "s" => self.source }
-      end
-      regexp
+      {:json_class => 'Regexp', "o" => regexp.options, "s" => regexp.source }
     end
 
     # Having Active Support JSON loaded somehow kills the formatting of pretty_generate for objects.
@@ -49,5 +52,14 @@ def remove_unicode json
       json.gsub(/\\u([0-9A-Za-z]{4})/) {|s| [$1.to_i(16)].pack("U")}
     end
 
+    def warn_about_regexp(thing)
+      thing.instance_variables.each do | iv_name |
+        iv = thing.instance_variable_get(iv_name)
+        if iv.is_a?(Regexp)
+          require 'pact/configuration'
+          Pact.configuration.error_stream.puts("WARN: Instance variable #{iv_name} for class #{thing.class.name} is a Regexp and isn't been serialized properly. Please raise an issue at https://github.com/pact-foundation/pact-support/issues/new.")
+        end
+      end
+    end
   end
 end
diff --git a/lib/pact/term.rb b/lib/pact/term.rb
index 388dbd9..b2b4d05 100644
--- a/lib/pact/term.rb
+++ b/lib/pact/term.rb
@@ -31,7 +31,7 @@ def initialize(attributes = {})
     end
 
     def to_hash
-      { json_class: self.class.name, data: { generate: generate, matcher: fix_regexp(matcher)} }
+      { json_class: self.class.name, data: { generate: generate, matcher: fix_regexp(matcher) } }
     end
 
     def as_json(options = {})
diff --git a/spec/lib/pact/consumer_contract/active_support_support_spec.rb b/spec/lib/pact/consumer_contract/active_support_support_spec.rb
index 338f015..a441662 100644
--- a/spec/lib/pact/consumer_contract/active_support_support_spec.rb
+++ b/spec/lib/pact/consumer_contract/active_support_support_spec.rb
@@ -1,24 +1,28 @@
-require 'spec_helper'
 require 'pact/shared/active_support_support'
+require 'pact/configuration'
 
 module Pact
-  describe ActiveSupportSupport do
 
-    include ActiveSupportSupport
+  class TestClassWithRegexpInstanceVariables
+    attr_accessor :pattern, :not_pattern
 
+    def initialize
+      @pattern = /foo/
+      @not_pattern = "bar"
+    end
+  end
+  describe ActiveSupportSupport do
+    include ActiveSupportSupport
 
     describe "fix_regexp" do
       let(:regexp) { /moose/ }
 
       subject { fix_regexp regexp }
 
-      it "returns the original regexp" do
-        expect(subject).to be(regexp)
-      end
-
       it "fixes the as_json method for Regexp that ActiveSupport tramples beneath its destructive hooves of destruction" do
         expect(subject.to_json).to eq("{\"json_class\":\"Regexp\",\"o\":0,\"s\":\"moose\"}")
       end
+
     end
 
     describe "fix_all_the_things" do
@@ -28,16 +32,36 @@ module Pact
 
       subject { fix_all_the_things(hash) }
 
-      it "returns the original object" do
-        expect(subject).to be(hash)
-      end
-
       it "finds all the Regexp objects in hashes or Pact class attributes and fixes the as_json method" do
         json = subject.to_json
         expect(json).to include("{\"json_class\":\"Regexp\",\"o\":0,\"s\":\"a*b\"}")
         expect(json).to include("{\"json_class\":\"Regexp\",\"o\":0,\"s\":\"blah\"}")
         expect(json).to include("{\"json_class\":\"Regexp\",\"o\":0,\"s\":\"alligator\"}")
       end
+
+      context "with Pact class that have Regexp instance variables" do
+        before do
+          allow(Pact).to receive_message_chain(:configuration, :error_stream).and_return(error_stream)
+        end
+
+        let(:error_stream) { double('stream', puts: nil) }
+        let(:thing_to_serialize) do
+          {
+            something: {
+              blah: [ TestClassWithRegexpInstanceVariables.new ]
+            }
+          }
+        end
+
+        subject { fix_all_the_things(thing_to_serialize) }
+
+        context "when ActiveSupportSupport is defined" do
+          it "prints a warning", skip: ENV['LOAD_ACTIVE_SUPPORT'] != 'true' do
+            expect(error_stream).to receive(:puts).with("WARN: Instance variable @pattern for class Pact::TestClassWithRegexpInstanceVariables is a Regexp and isn't been serialized properly. Please raise an issue at https://github.com/pact-foundation/pact-support/issues/new.")
+            subject.to_json
+          end
+        end
+      end
     end
 
     describe "fix_json_formatting" do