diff --git a/.rubocop.yml b/.rubocop.yml
index 0b542bd..ca1e87a 100644
--- a/.rubocop.yml
+++ b/.rubocop.yml
@@ -1,5 +1,5 @@
 AllCops:
-  TargetRubyVersion: 2.3
+  TargetRubyVersion: 2.2
 Metrics/AbcSize:
   Enabled: false
 Metrics/CyclomaticComplexity:
diff --git a/bora.gemspec b/bora.gemspec
index 5e9a6d6..0d91ba9 100644
--- a/bora.gemspec
+++ b/bora.gemspec
@@ -1,5 +1,3 @@
-# coding: utf-8
-
 lib = File.expand_path('../lib', __FILE__)
 $LOAD_PATH.unshift(lib) unless $LOAD_PATH.include?(lib)
 require 'bora/version'
@@ -29,8 +27,8 @@ Gem::Specification.new do |spec|
 
   spec.add_development_dependency 'bundler', '~> 1.7'
   spec.add_development_dependency 'hashie', '~> 3.4.6'
+  spec.add_development_dependency 'pry'
   spec.add_development_dependency 'rspec', '~> 3.0'
-  spec.add_development_dependency 'simplecov', '~> 0.12'
   spec.add_development_dependency 'rubocop'
-  spec.add_development_dependency 'pry'
+  spec.add_development_dependency 'simplecov', '~> 0.12'
 end
diff --git a/lib/bora.rb b/lib/bora.rb
index 2384cbb..8a8c35e 100644
--- a/lib/bora.rb
+++ b/lib/bora.rb
@@ -33,7 +33,7 @@ def stack(stack_name)
   end
 
   def rake_tasks
-    @templates.each { |_, t| t.rake_tasks }
+    @templates.each_value { |_, t| t.rake_tasks }
   end
 
   protected
diff --git a/lib/bora/cli_base.rb b/lib/bora/cli_base.rb
index 0c53fbc..573c2e7 100644
--- a/lib/bora/cli_base.rb
+++ b/lib/bora/cli_base.rb
@@ -3,7 +3,7 @@
 class Bora
   class CliBase < Thor
     # Fix for incorrect subcommand help. See https://github.com/erikhuda/thor/issues/261
-    def self.banner(command, _namespace = nil, subcommand = false)
+    def self.banner(command, _namespace = nil, _subcommand = false)
       subcommand = subcommand_prefix
       subcommand_str = subcommand ? " #{subcommand}" : ''
       "#{basename}#{subcommand_str} #{command.usage}"
diff --git a/lib/bora/resolver/ami.rb b/lib/bora/resolver/ami.rb
index 49ef1e0..57a6615 100644
--- a/lib/bora/resolver/ami.rb
+++ b/lib/bora/resolver/ami.rb
@@ -41,7 +41,7 @@ def resolve(uri)
         end
 
         raise NoAMI, "No Matching AMI's for prefix #{ami_prefix}" if images.empty?
-        images.sort! { |a, b| DateTime.parse(a.creation_date) <=> DateTime.parse(b.creation_date) }.last.image_id
+        images.sort! { |a, b| Time.parse(a.creation_date) <=> Time.parse(b.creation_date) }.last.image_id
       end
     end
   end
diff --git a/lib/bora/template.rb b/lib/bora/template.rb
index 6705512..3499f60 100644
--- a/lib/bora/template.rb
+++ b/lib/bora/template.rb
@@ -29,13 +29,14 @@ def stacks
     end
 
     def rake_tasks
-      @stacks.each { |_, s| s.rake_tasks }
+      @stacks.each_value { |_, s| s.rake_tasks }
     end
 
     private
 
     def resolve_stack_config(template_config, stack_config, override_config)
-      inheritable_properties(template_config).deep_merge!(stack_config).merge(overridable_properties(override_config))
+      template_config_copy = Marshal.load(Marshal.dump(template_config))
+      inheritable_properties(template_config_copy).deep_merge!(stack_config).merge(overridable_properties(override_config))
     end
 
     def inheritable_properties(config)