diff --git a/lib/census_api.rb b/lib/census_api.rb
index 09fcbcc87..d290a1bbf 100644
--- a/lib/census_api.rb
+++ b/lib/census_api.rb
@@ -1,5 +1,6 @@
-include DocumentParser
 class CensusApi
+  include DocumentParser
+
   def call(document_type, document_number)
     response = nil
     get_document_number_variants(document_type, document_number).each do |variant|
diff --git a/lib/local_census.rb b/lib/local_census.rb
index 1f6d3f903..dc566f5fb 100644
--- a/lib/local_census.rb
+++ b/lib/local_census.rb
@@ -1,5 +1,6 @@
-include DocumentParser
 class LocalCensus
+  include DocumentParser
+
   def call(document_type, document_number)
     record = nil
     get_document_number_variants(document_type, document_number).each do |variant|
diff --git a/lib/remote_census_api.rb b/lib/remote_census_api.rb
index c5db70365..99ed06445 100644
--- a/lib/remote_census_api.rb
+++ b/lib/remote_census_api.rb
@@ -1,5 +1,6 @@
-include DocumentParser
 class RemoteCensusApi
+  include DocumentParser
+
   def call(document_type, document_number, date_of_birth, postal_code)
     response = nil
     get_document_number_variants(document_type, document_number).each do |variant|
diff --git a/spec/lib/document_parser_spec.rb b/spec/lib/document_parser_spec.rb
index 6162bc9e7..be8b254ae 100644
--- a/spec/lib/document_parser_spec.rb
+++ b/spec/lib/document_parser_spec.rb
@@ -1,35 +1,44 @@
 require "rails_helper"
-include DocumentParser
 
 describe DocumentParser do
+  before do
+    dummy_class = Class.new do
+      include DocumentParser
+    end
+
+    stub_const("DummyClass", dummy_class)
+  end
+
+  let(:dummy) { DummyClass.new }
+
   describe "#get_document_number_variants" do
     it "returns no variants when document_number is not defined" do
-      expect(DocumentParser.get_document_number_variants("1", "")).to be_empty
+      expect(dummy.get_document_number_variants("1", "")).to be_empty
     end
 
     it "trims and cleans up entry" do
-      expect(DocumentParser.get_document_number_variants(2, "  1 2@ 34")).to eq(["1234"])
+      expect(dummy.get_document_number_variants(2, "  1 2@ 34")).to eq(["1234"])
     end
 
     it "returns only one try for passports & residence cards" do
-      expect(DocumentParser.get_document_number_variants(2, "1234")).to eq(["1234"])
-      expect(DocumentParser.get_document_number_variants(3, "1234")).to eq(["1234"])
+      expect(dummy.get_document_number_variants(2, "1234")).to eq(["1234"])
+      expect(dummy.get_document_number_variants(3, "1234")).to eq(["1234"])
     end
 
     it "takes only the last 8 digits for dnis and resicence cards" do
-      expect(DocumentParser.get_document_number_variants(1, "543212345678")).to eq(["12345678"])
+      expect(dummy.get_document_number_variants(1, "543212345678")).to eq(["12345678"])
     end
 
     it "tries all the dni variants padding with zeroes" do
-      expect(DocumentParser.get_document_number_variants(1, "0123456"))
+      expect(dummy.get_document_number_variants(1, "0123456"))
         .to eq(["123456", "0123456", "00123456"])
 
-      expect(DocumentParser.get_document_number_variants(1, "00123456"))
+      expect(dummy.get_document_number_variants(1, "00123456"))
         .to eq(["123456", "0123456", "00123456"])
     end
 
     it "adds upper and lowercase letter when the letter is present" do
-      expect(DocumentParser.get_document_number_variants(1, "1234567A"))
+      expect(dummy.get_document_number_variants(1, "1234567A"))
         .to eq(%w[1234567 01234567 1234567a 1234567A 01234567a 01234567A])
     end
   end