diff --git a/ext/rugged/extconf.rb b/ext/rugged/extconf.rb
index 69634df9d..c1ad0b3ef 100644
--- a/ext/rugged/extconf.rb
+++ b/ext/rugged/extconf.rb
@@ -98,7 +98,7 @@ def self.run_cmake(timeout, args)
   end
 
   Dir.chdir(LIBGIT2_DIR) do
-    Dir.mkdir("build") if !Dir.exists?("build")
+    Dir.mkdir("build") if !Dir.exist?("build")
 
     Dir.chdir("build") do
       # On Windows, Ruby-DevKit is MSYS-based, so ensure to use MSYS Makefiles.