diff --git a/lib/ext/string.rb b/lib/ext/string.rb
index <HASH>..<HASH> 100644
--- a/lib/ext/string.rb
+++ b/lib/ext/string.rb
@@ -1,5 +1,5 @@
 class String
   def camel_case
     split('_').inject([]){ |buffer,e| buffer.push(buffer.empty? ? e : e.capitalize) }.join
-  end
+  end unless method_defined?(:camel_case)
 end
\ No newline at end of file
Implements the `#camel_case` method on `String` only if it isn't
already there.