diff --git a/.rubocop.yml b/.rubocop.yml
index 223d3aae..652f08fb 100644
--- a/.rubocop.yml
+++ b/.rubocop.yml
@@ -31,7 +31,7 @@ HashSyntax:
   EnforcedStyle: ruby19
 SpaceAroundEqualsInParameterDefault:
   EnforcedStyle: no_space
-Blocks:
+BlockDelimiters:
   Enabled: false
 PerlBackrefs:
   Enabled: false
diff --git a/middleman-core/lib/middleman-core/extensions/asset_hash.rb b/middleman-core/lib/middleman-core/extensions/asset_hash.rb
index 531b4442..39f1a069 100644
--- a/middleman-core/lib/middleman-core/extensions/asset_hash.rb
+++ b/middleman-core/lib/middleman-core/extensions/asset_hash.rb
@@ -75,7 +75,7 @@ class Middleman::Extensions::AssetHash < ::Middleman::Extension
     # Render through the Rack interface so middleware and mounted apps get a shot
     response = @rack_client.get(URI.escape(resource.destination_path),
                                 'bypass_inline_url_rewriter_asset_hash' => 'true'
-                                )
+                               )
 
     raise "#{resource.path} should be in the sitemap!" unless response.status == 200
 
diff --git a/middleman-core/lib/middleman-core/extensions/lorem.rb b/middleman-core/lib/middleman-core/extensions/lorem.rb
index 32f1c6c1..91a0612d 100644
--- a/middleman-core/lib/middleman-core/extensions/lorem.rb
+++ b/middleman-core/lib/middleman-core/extensions/lorem.rb
@@ -152,8 +152,8 @@ class Middleman::Extensions::Lorem < ::Middleman::Extension
         color            = options[:color]
 
         if options[:random_color]
-          background_color = hex.shuffle[0...6].join
-          color = hex.shuffle[0...6].join
+          background_color = hex.sample(6).join
+          color = hex.sample(6).join
         end
 
         src << "/#{background_color.sub(/^#/, '')}" if background_color
diff --git a/middleman-core/lib/middleman-core/middleware/inline_url_rewriter.rb b/middleman-core/lib/middleman-core/middleware/inline_url_rewriter.rb
index 1151800c..b1eddd11 100644
--- a/middleman-core/lib/middleman-core/middleware/inline_url_rewriter.rb
+++ b/middleman-core/lib/middleman-core/middleware/inline_url_rewriter.rb
@@ -89,6 +89,7 @@ module Middleman
           File.fnmatch(value, validator)
         else
           # If some unknown thing, don't ignore
+          false
         end
       end
     end
diff --git a/middleman-core/lib/middleman-core/sitemap/extensions/proxies.rb b/middleman-core/lib/middleman-core/sitemap/extensions/proxies.rb
index 536200db..da23c9e9 100644
--- a/middleman-core/lib/middleman-core/sitemap/extensions/proxies.rb
+++ b/middleman-core/lib/middleman-core/sitemap/extensions/proxies.rb
@@ -74,7 +74,7 @@ module Middleman
               locals: md.delete(:locals) || {},
               page: md.delete(:data) || {},
               options: md
-                           )
+            )
           end
         end
       end
diff --git a/middleman-core/lib/middleman-core/sitemap/extensions/redirects.rb b/middleman-core/lib/middleman-core/sitemap/extensions/redirects.rb
index 84f96749..418f5d73 100644
--- a/middleman-core/lib/middleman-core/sitemap/extensions/redirects.rb
+++ b/middleman-core/lib/middleman-core/sitemap/extensions/redirects.rb
@@ -63,7 +63,7 @@ module Middleman
           url = ::Middleman::Util.url_for(@store.app, @request_path,
                                           relative: false,
                                           find_resource: true
-          )
+                                         )
 
           if output
             output.call(path, url)
diff --git a/middleman-core/lib/middleman-core/sources.rb b/middleman-core/lib/middleman-core/sources.rb
index 005bdde1..87b0d957 100644
--- a/middleman-core/lib/middleman-core/sources.rb
+++ b/middleman-core/lib/middleman-core/sources.rb
@@ -14,6 +14,8 @@ module Middleman
     extend Forwardable
     include Contracts
 
+    Matcher = Or[Regexp, RespondTo[:call]]
+
     # A reference to the current app.
     Contract IsA['Middleman::Application']
     attr_reader :app
@@ -246,28 +248,24 @@ module Middleman
     # Backwards compatible change handler.
     #
     # @param [nil,Regexp] matcher A Regexp to match the change path against
-    # Contract Maybe[Regexp] => Any
+    Contract Maybe[Matcher] => Any
     def changed(matcher=nil, &block)
       on_change :source do |updated, _removed|
-        updated.select { |f|
-          matcher.nil? ? true : matches?(matcher, f)
-        }.each do |f|
-          block.call(f[:relative_path])
-        end
+        updated
+          .select { |f| matcher.nil? ? true : matches?(matcher, f) }
+          .each { |f| block.call(f[:relative_path]) }
       end
     end
 
     # Backwards compatible delete handler.
     #
     # @param [nil,Regexp] matcher A Regexp to match the change path against
-    # Contract Maybe[Regexp] => Any
+    Contract Maybe[Matcher] => Any
     def deleted(matcher=nil, &block)
       on_change :source do |_updated, removed|
-        removed.select { |f|
-          matcher.nil? ? true : matches?(matcher, f)
-        }.each do |f|
-          block.call(f[:relative_path])
-        end
+        removed
+          .select { |f| matcher.nil? ? true : matches?(matcher, f) }
+          .each { |f| block.call(f[:relative_path]) }
       end
     end
 
@@ -287,7 +285,7 @@ module Middleman
     # @param [Regexp, #call] validator The match validator.
     # @param [Middleman::SourceFile] file The file to check.
     # @return [Boolean]
-    Contract Or[Regexp, RespondTo[:call]], SourceFile => Bool
+    Contract Matcher, SourceFile => Bool
     def matches?(validator, file)
       path = file[:relative_path]
       if validator.is_a? Regexp
diff --git a/middleman-core/lib/middleman-core/sources/source_watcher.rb b/middleman-core/lib/middleman-core/sources/source_watcher.rb
index e09a8aba..6722727f 100644
--- a/middleman-core/lib/middleman-core/sources/source_watcher.rb
+++ b/middleman-core/lib/middleman-core/sources/source_watcher.rb
@@ -252,7 +252,7 @@ module Middleman
 
     Contract Pathname => Pathname
     def strip_extensions(p)
-      p = p.sub_ext('') while ::Tilt[p.to_s] || p.extname === '.html'
+      p = p.sub_ext('') while ::Tilt[p.to_s] || p.extname == '.html'
       Pathname(p.to_s + '.*')
     end
 
@@ -262,9 +262,9 @@ module Middleman
     # @return [Boolean]
     Contract IsA['Middleman::SourceFile'] => Bool
     def valid?(file)
-      globally_valid = @validator.call(file) && !globally_ignored?(file)
+      return false unless @validator.call(file) && !globally_ignored?(file)
 
-      globally_valid && if @only.empty?
+      if @only.empty?
         !@ignored.call(file)
       else
         @only.any? { |reg| reg.match(file[:relative_path].to_s) }
diff --git a/middleman-core/lib/middleman-core/util.rb b/middleman-core/lib/middleman-core/util.rb
index 44f7b3f7..945c4f96 100644
--- a/middleman-core/lib/middleman-core/util.rb
+++ b/middleman-core/lib/middleman-core/util.rb
@@ -87,13 +87,11 @@ module Middleman
         end
       end
 
-      def method_missing(key, *args)
+      def method_missing(key, *_args)
         if key?(key.to_sym)
           self[key.to_sym]
         elsif key?(key.to_s)
           self[key.to_s]
-        else
-          super
         end
       end
     end
@@ -131,7 +129,6 @@ module Middleman
       end
     end
 
-
     # Normalize a path to not include a leading slash
     # @param [String] path
     # @return [String]