diff --git a/Gemfile.lock b/Gemfile.lock
index 4d3f3993..477c6d54 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -68,7 +68,6 @@ GEM
     docile (1.3.1)
     equalizer (0.0.11)
     erubis (2.7.0)
-    ffi (1.9.25)
     flay (2.10.0)
       erubis (~> 2.7.0)
       path_expander (~> 1.0)
@@ -165,7 +164,6 @@ PLATFORMS
 DEPENDENCIES
   bundler (~> 1.10)
   devtools (~> 0.1.21)
-  ffi (~> 1.9.6)
   mutant!
   parallel (~> 1.3)
 
diff --git a/mutant.gemspec b/mutant.gemspec
index 2be151a2..cea89165 100644
--- a/mutant.gemspec
+++ b/mutant.gemspec
@@ -40,6 +40,5 @@ Gem::Specification.new do |gem|
 
   gem.add_development_dependency('bundler',  '~> 1.10')
   gem.add_development_dependency('devtools', '~> 0.1.21')
-  gem.add_development_dependency('ffi',      '~> 1.9.6')
   gem.add_development_dependency('parallel', '~> 1.3')
 end
diff --git a/spec/support/rb_bug.rb b/spec/support/rb_bug.rb
deleted file mode 100644
index 557137db..00000000
--- a/spec/support/rb_bug.rb
+++ /dev/null
@@ -1,18 +0,0 @@
-# frozen_string_literal: true
-
-require 'ffi'
-
-# @api private
-module RbBug
-  extend FFI::Library
-  ffi_lib 'ruby'
-  attach_function :rb_bug, %i[string varargs], :void
-
-  # Call the test bug
-  #
-  # @return [undefined]
-  def self.call
-    rb_bug('%s', :string, 'test bug')
-  end
-
-end # RbBug