diff --git a/Gemfile b/Gemfile
index c4513b04..a8146ca6 100644
--- a/Gemfile
+++ b/Gemfile
@@ -38,7 +38,7 @@ gem 'therubyracer', '~> 0.12.3', platforms: :ruby
 gem 'therubyrhino', '>= 2.0', platforms: :jruby
 
 # Code Quality
-gem 'rubocop', '~> 0.52', require: false
+gem 'rubocop', '0.59.0', require: false
 gem 'simplecov', '~> 0.10', require: false
 
 # Middleman itself
diff --git a/Gemfile.lock b/Gemfile.lock
index 897035e0..eb3b07f4 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -19,13 +19,15 @@ PATH
       fastimage (~> 2.0)
       hamster (~> 3.0)
       hashie (~> 3.4)
-      i18n (~> 0.8)
+      i18n (~> 0.9.0)
       listen (~> 3.0)
       memoist (~> 0.14)
+      oj (~> 3.7)
       padrino-helpers (~> 0.13.0)
       parallel
       rack (>= 1.4.5, < 3)
       sass (>= 3.4)
+      sassc (~> 1.10)
       servolux
       tilt (~> 2.0)
       uglifier (~> 3.0)
@@ -82,10 +84,10 @@ GEM
       gherkin (~> 5.1.0)
       multi_json (>= 1.7.5, < 2.0)
       multi_test (>= 0.1.2)
-    cucumber-core (3.2.0)
+    cucumber-core (3.2.1)
       backports (>= 3.8.0)
       cucumber-tag_expressions (~> 1.1.0)
-      gherkin (>= 5.0.0)
+      gherkin (~> 5.0)
     cucumber-expressions (6.0.1)
     cucumber-tag_expressions (1.1.1)
     cucumber-wire (0.0.1)
@@ -112,13 +114,13 @@ GEM
     json (2.1.0)
     kramdown (1.17.0)
     libv8 (3.16.14.19)
-    liquid (4.0.0)
+    liquid (4.0.1)
     listen (3.1.5)
       rb-fsevent (~> 0.9, >= 0.9.4)
       rb-inotify (~> 0.9, >= 0.9.7)
       ruby_dep (~> 1.2)
     memoist (0.16.0)
-    method_source (0.9.0)
+    method_source (0.9.1)
     mime-types (3.2.2)
       mime-types-data (~> 3.2015)
     mime-types-data (3.2018.0812)
@@ -130,6 +132,7 @@ GEM
     nio4r (2.3.1)
     nokogiri (1.8.5)
       mini_portile2 (~> 2.3.0)
+    oj (3.7.0)
     padrino-helpers (0.13.3.4)
       i18n (~> 0.6, >= 0.6.7)
       padrino-support (= 0.13.3.4)
@@ -137,21 +140,21 @@ GEM
     padrino-support (0.13.3.4)
       activesupport (>= 3.1)
     parallel (1.12.1)
-    parser (2.5.1.2)
+    parser (2.5.3.0)
       ast (~> 2.4.0)
     powerpack (0.1.2)
-    pry (0.11.3)
+    pry (0.12.0)
       coderay (~> 1.1.0)
       method_source (~> 0.9.0)
     pry-rescue (1.4.5)
       interception (>= 0.5)
       pry
-    pry-stack_explorer (0.4.9.2)
+    pry-stack_explorer (0.4.9.3)
       binding_of_caller (>= 0.7)
       pry (>= 0.9.11)
     public_suffix (3.0.3)
-    rack (2.0.5)
-    rack-protection (2.0.3)
+    rack (2.0.6)
+    rack-protection (2.0.4)
       rack
     rack-test (1.1.0)
       rack (>= 1.0, < 3)
@@ -168,7 +171,7 @@ GEM
       rspec-mocks (~> 3.8.0)
     rspec-core (3.8.0)
       rspec-support (~> 3.8.0)
-    rspec-expectations (3.8.1)
+    rspec-expectations (3.8.2)
       diff-lcs (>= 1.2.0, < 2.0)
       rspec-support (~> 3.8.0)
     rspec-mocks (3.8.0)
@@ -189,7 +192,7 @@ GEM
       celluloid (= 0.16.0)
       celluloid-io (= 0.16.2)
       timers (~> 4.0.1)
-    sass (3.5.7)
+    sass (3.7.1)
       sass-listen (~> 4.0.0)
     sass-listen (4.0.0)
       rb-fsevent (~> 0.9, >= 0.9.4)
@@ -203,10 +206,10 @@ GEM
       json (>= 1.8, < 3)
       simplecov-html (~> 0.10.0)
     simplecov-html (0.10.2)
-    sinatra (2.0.3)
+    sinatra (2.0.4)
       mustermann (~> 1.0)
       rack (~> 2.0)
-      rack-protection (= 2.0.3)
+      rack-protection (= 2.0.4)
       tilt (~> 2.0)
     slim (4.0.1)
       temple (>= 0.7.6, < 0.9)
@@ -254,7 +257,7 @@ DEPENDENCIES
   rake (~> 10.3)
   redcarpet (>= 3.1)
   rspec (~> 3.0)
-  rubocop (~> 0.52)
+  rubocop (= 0.59.0)
   rubydns (~> 1.0.1)
   sassc (~> 1.10)
   simplecov (~> 0.10)
diff --git a/middleman-core/middleman-core.gemspec b/middleman-core/middleman-core.gemspec
index 6cb87758..2883549a 100644
--- a/middleman-core/middleman-core.gemspec
+++ b/middleman-core/middleman-core.gemspec
@@ -45,10 +45,12 @@ Gem::Specification.new do |s|
 
   # Minify CSS
   s.add_dependency('sass', ['>= 3.4'])
+  s.add_dependency('sassc', ['~> 1.10'])
 
   # Minify JS
   s.add_dependency('uglifier', ['~> 3.0'])
   s.add_dependency('execjs', ['~> 2.0'])
+  s.add_dependency('oj', ['~> 3.7'])
 
   # Testing
   s.add_dependency('contracts', ['~> 0.16.0'])