diff --git a/lib/flexmock/minitest_integration.rb b/lib/flexmock/minitest_integration.rb
index 0f18a3f..6f3cae1 100644
--- a/lib/flexmock/minitest_integration.rb
+++ b/lib/flexmock/minitest_integration.rb
@@ -98,7 +98,11 @@ def check(msg, &block)
     end
 
     def assertion_failed_error
-      MiniTest::Assertion
+      if defined?(::Minitest)
+        ::Minitest::Assertion
+      else
+        MiniTest::Assertion
+      end
     end
 
     def check_failed_error
diff --git a/lib/flexmock/test_unit_integration.rb b/lib/flexmock/test_unit_integration.rb
index 5af1b6e..f1035a9 100644
--- a/lib/flexmock/test_unit_integration.rb
+++ b/lib/flexmock/test_unit_integration.rb
@@ -68,7 +68,7 @@ def check(msg, &block)
     def assertion_failed_error
       defined?(Test::Unit::AssertionFailedError) ?
         Test::Unit::AssertionFailedError :
-        MiniTest::Assertion
+        Minitest::Assertion
     end
 
     def check_failed_error
diff --git a/lib/flexmock/test_unit_testcase_extensions.rb b/lib/flexmock/test_unit_testcase_extensions.rb
index 081f700..c3a74f6 100644
--- a/lib/flexmock/test_unit_testcase_extensions.rb
+++ b/lib/flexmock/test_unit_testcase_extensions.rb
@@ -30,8 +30,8 @@ def teardown
   end
 end
 
-if defined?(MiniTest)
-  module MiniTest
+if defined?(Minitest)
+  module Minitest
     class Unit
       class TestCase
         FlexMock::GenericTestCase.define_extensions_on(self)
diff --git a/lib/flexmock/version.rb b/lib/flexmock/version.rb
index 6c70687..301b30e 100644
--- a/lib/flexmock/version.rb
+++ b/lib/flexmock/version.rb
@@ -1,3 +1,3 @@
 class FlexMock
-    VERSION = "2.3.6"
+    VERSION = "2.3.7"
 end