diff --git a/lib/warden/jwt_auth.rb b/lib/warden/jwt_auth.rb
index 4f41e80..5ea4396 100644
--- a/lib/warden/jwt_auth.rb
+++ b/lib/warden/jwt_auth.rb
@@ -19,6 +19,8 @@ module Warden
   module JWTAuth
     extend Dry::Configurable
 
+    module_function
+
     def symbolize_keys(hash)
       hash.transform_keys(&:to_sym)
     end
@@ -36,8 +38,6 @@ def constantize_values(hash)
       end
     end
 
-    module_function :constantize_values, :symbolize_keys, :upcase_first_items
-
     # The secret used to encode the token
     setting :secret
 
diff --git a/spec/support/shared_contexts/configuration.rb b/spec/support/shared_contexts/configuration.rb
index 2adecf6..b773187 100644
--- a/spec/support/shared_contexts/configuration.rb
+++ b/spec/support/shared_contexts/configuration.rb
@@ -13,6 +13,7 @@
       config.mappings = { user: Fixtures::UserRepo }
       config.token_header = 'Authorization'
       config.aud_header = 'TEST_AUD'
+      config.issuer = 'http://example.com'
     end
   end
 
diff --git a/spec/warden/jwt_auth/strategy_spec.rb b/spec/warden/jwt_auth/strategy_spec.rb
index a4898c7..89530c6 100644
--- a/spec/warden/jwt_auth/strategy_spec.rb
+++ b/spec/warden/jwt_auth/strategy_spec.rb
@@ -31,30 +31,25 @@
       end
     end
 
-    context 'when issuer is configured' do
-      let(:token) { Warden::JWTAuth::TokenEncoder.new.call({ issuer: issuer }) }
-      let(:env) { { 'HTTP_AUTHORIZATION' => "Bearer #{token}" } }
-      let(:issuer) { 'http://example.com' }
-      let(:strategy) { described_class.new(env, :user) }
+    context 'when issuer claim is configured and it matches the configured issuer' do
+      it 'returns true' do
+        token = Warden::JWTAuth::TokenEncoder.new.call({ 'iss' => Warden::JWTAuth.config.issuer })
+        env = { 'HTTP_AUTHORIZATION' => "Bearer #{token}" }
 
-      before do
-        Warden::JWTAuth.configure do |config|
-          config.issuer = issuer
-        end
-      end
+        strategy = described_class.new(env, :user)
 
-      context 'when the issuer claim matches the configured issuer' do
-        it 'returns true' do
-          expect(strategy).to be_valid
-        end
+        expect(strategy).to be_valid
       end
+    end
 
-      context 'when the issuer claim does not match the configured issuer' do
-        let(:token) { Warden::JWTAuth::TokenEncoder.new.call({ 'iss' => 'http://example.org' }) }
+    context "when issuer claim is configured and it doesn't match the configured issuer" do
+      it 'returns false' do
+        token = Warden::JWTAuth::TokenEncoder.new.call({ 'iss' => Warden::JWTAuth.config.issuer + 'aaa' })
+        env = { 'HTTP_AUTHORIZATION' => "Bearer #{token}" }
 
-        it 'returns false' do
-          expect(strategy).not_to be_valid
-        end
+        strategy = described_class.new(env, :user)
+
+        expect(strategy).not_to be_valid
       end
     end
   end