diff --git a/lib/noosfero/api/helpers.rb b/lib/noosfero/api/helpers.rb
index d7bb8e6..0347dfe 100644
--- a/lib/noosfero/api/helpers.rb
+++ b/lib/noosfero/api/helpers.rb
@@ -262,8 +262,7 @@
       #              captcha_helpers           #
       ##########################################
 
-      def test_captcha(remote_ip, params, _environment = nil)
-        environment ||= _environment
+      def test_captcha(remote_ip, params, environment)
         d = environment.api_captcha_settings
         return true unless d[:enabled] == true
 
diff --git a/lib/noosfero/api/session.rb b/lib/noosfero/api/session.rb
index 1698f67..149af79 100644
--- a/lib/noosfero/api/session.rb
+++ b/lib/noosfero/api/session.rb
@@ -41,7 +41,7 @@ module Noosfero
         attrs = attributes_for_keys [:email, :login, :password, :password_confirmation] + environment.signup_person_fields
         remote_ip = (request.respond_to?(:remote_ip) && request.remote_ip) || (env && env['REMOTE_ADDR'])
 
-        if not test_captcha(remote_ip, params, environment) == true
+        unless test_captcha(remote_ip, params, environment) == true
           render_api_error!(_('Please solve the test in order to register.'), 401)
           return
         end
diff --git a/test/unit/api/helpers_test.rb b/test/unit/api/helpers_test.rb
index f947309..1a8e99f 100644
--- a/test/unit/api/helpers_test.rb
+++ b/test/unit/api/helpers_test.rb
@@ -164,8 +164,7 @@ class APIHelpersTest < ActiveSupport::TestCase
 
   should 'do not test captcha when there are no settings' do
     environment = Environment.new
-    stubs(:environment).returns(environment)
-    assert test_captcha("127.0.0.1", {})
+    assert test_captcha("127.0.0.1", {}, environment)
   end
 
   should 'do not test captcha when captcha is disabled on settings' do
@@ -173,8 +172,7 @@ class APIHelpersTest < ActiveSupport::TestCase
     environment.api_captcha_settings = {
         enabled: false,
     }
-    stubs(:environment).returns(environment)
-    assert test_captcha("127.0.0.1", {})
+    assert test_captcha("127.0.0.1", {}, environment)
   end
 
   should 'fail display recaptcha v1' do
@@ -187,8 +185,7 @@ class APIHelpersTest < ActiveSupport::TestCase
         public_key:   '6LdsWAcTAAAAAChTUUD6yu9fCDhdIZzNd7F53zf-',
         verify_uri:   'https://www.google.com/recaptcha/api/verify',
     }
-    stubs(:environment).returns(environment)
-    assert_equal test_captcha("127.0.0.1", {}), "Missing captcha data"
+    assert_equal test_captcha("127.0.0.1", {}, environment), "Missing captcha data"
   end
 
   should 'fail display recaptcha v2' do
@@ -201,8 +198,7 @@ class APIHelpersTest < ActiveSupport::TestCase
         public_key:   '6LdsWAcTAAAAAChTUUD6yu9fCDhdIZzNd7F53zf-',
         verify_uri:   'https://www.google.com/recaptcha/api/siteverify',
     }
-    stubs(:environment).returns(environment)
-    assert_equal test_captcha("127.0.0.1", {}), "Missing captcha data"
+    assert_equal test_captcha("127.0.0.1", {}, environment), "Missing captcha data"
   end
 
   should 'fail display Serpro captcha' do
@@ -212,8 +208,7 @@ class APIHelpersTest < ActiveSupport::TestCase
         provider: 'serpro',
         serpro_client_id:  '0000000000000000',
     }
-    stubs(:environment).returns(environment)
-    assert_equal test_captcha("127.0.0.1", {}), "Missing captcha data"
+    assert_equal test_captcha("127.0.0.1", {}, environment), "Missing captcha data"
   end
 
   should 'render not_found if endpoint is unavailable' do
--
libgit2 0.21.2