diff --git a/spec/cocaine/command_line_spec.rb b/spec/cocaine/command_line_spec.rb
index 27f823b..ab1aa37 100644
--- a/spec/cocaine/command_line_spec.rb
+++ b/spec/cocaine/command_line_spec.rb
@@ -152,7 +152,7 @@
   end
 
   it "detects that the system is windows (mingw)" do
-    stub_os("mingw")
+    on_mingw!
     Cocaine::CommandLine.unix?.should be_false
   end
 
diff --git a/spec/support/stub_os.rb b/spec/support/stub_os.rb
index 3a7ef4d..4d43c35 100644
--- a/spec/support/stub_os.rb
+++ b/spec/support/stub_os.rb
@@ -7,6 +7,10 @@ def on_unix!
     stub_os('darwin11.0.0')
   end
 
+  def on_mingw!
+    stub_os('mingw')
+  end
+
   def stub_os(host_string)
     # http://blog.emptyway.com/2009/11/03/proper-way-to-detect-windows-platform-in-ruby/
     RbConfig::CONFIG.stubs(:[]).with('host_os').returns(host_string)