README.rdoc in rake-compiler-0.9.2 vs README.rdoc in rake-compiler-0.9.3

@@ -69,10 +69,11 @@
 Now the fun part. It's time to introduce the code to your projects Rakefile
 to tell it to use rake-compiler to build your extension:
 
     # File: extconf.rb
 
-    # this line should already exist
+    # these lines must exist already
+    require 'mkmf'
     create_makefile('hello_world')
 
 
     # File: Rakefile