diff --git a/lib/peano/rspec-ext.rb b/lib/peano/rspec-ext.rb
deleted file mode 100644
index ccec7a7..0000000
--- a/lib/peano/rspec-ext.rb
+++ /dev/null
@@ -1,7 +0,0 @@
-require 'rspec'
-
-class RSpec::Core::ExampleGroup
-  def property_of(&block)
-    Rantly::Property.new(block)
-  end
-end
diff --git a/test/peano_test.rb b/test/peano_test.rb
index 4939f57..74bf74e 100644
--- a/test/peano_test.rb
+++ b/test/peano_test.rb
@@ -1,5 +1,4 @@
 require 'peano/peano'
-require 'peano/rspec-ext'
 require 'rantly/property'
 require 'rspec'
 
diff --git a/test/trampoline_test.rb b/test/trampoline_test.rb
index 0755471..df59c98 100644
--- a/test/trampoline_test.rb
+++ b/test/trampoline_test.rb
@@ -1,5 +1,4 @@
 require 'peano/trampoline'
-require 'peano/rspec-ext'
 require 'rantly/property'
 require 'rspec'