diff --git a/Gemfile b/Gemfile
index cd316552..a5000a6f 100644
--- a/Gemfile
+++ b/Gemfile
@@ -4,4 +4,5 @@ source 'https://rubygems.org'
 
 gemspec name: 'mutant'
 
+gem 'morpher',  git: 'https://github.com/mbj/morpher.git'
 gem 'devtools', git: 'https://github.com/rom-rb/devtools.git'
diff --git a/mutant.gemspec b/mutant.gemspec
index 70d82dba..696bd611 100644
--- a/mutant.gemspec
+++ b/mutant.gemspec
@@ -24,10 +24,10 @@ Gem::Specification.new do |gem|
   gem.required_ruby_version = '>= 2.1'
 
   gem.add_runtime_dependency('parser',        '~> 2.2.2')
-  gem.add_runtime_dependency('ast',           '~> 2.0')
+  gem.add_runtime_dependency('ast',           '~> 2.1')
   gem.add_runtime_dependency('diff-lcs',      '~> 1.2')
   gem.add_runtime_dependency('parallel',      '~> 1.3')
-  gem.add_runtime_dependency('morpher',       '~> 0.2.3')
+  gem.add_runtime_dependency('morpher',       '~> 0.2.4')
   gem.add_runtime_dependency('procto',        '~> 0.0.2')
   gem.add_runtime_dependency('abstract_type', '~> 0.0.7')
   gem.add_runtime_dependency('unparser',      '~> 0.2.4')