diff --git a/Gemfile b/Gemfile
index 04587679d..91e09e392 100644
--- a/Gemfile
+++ b/Gemfile
@@ -1,11 +1,11 @@
 source 'https://rubygems.org'
 
-gem 'rails', '~> 5.1.0'
+gem 'rails', '~> 5.2.0'
 
 # Use Puma as the app server
 gem 'puma', '~> 3.0'
 
-# requirement for rdf-rdfa / haml gem
+# requirement for rdf-rdfa 1.99 / haml 4 gem
 gem 'erubis'
 
 group :development, :test do
diff --git a/Gemfile.lock b/Gemfile.lock
index e037cfd04..720279342 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -1,25 +1,25 @@
 GEM
   remote: https://rubygems.org/
   specs:
-    actioncable (5.1.6)
-      actionpack (= 5.1.6)
+    actioncable (5.2.1.1)
+      actionpack (= 5.2.1.1)
       nio4r (~> 2.0)
-      websocket-driver (~> 0.6.1)
-    actionmailer (5.1.6)
-      actionpack (= 5.1.6)
-      actionview (= 5.1.6)
-      activejob (= 5.1.6)
+      websocket-driver (>= 0.6.1)
+    actionmailer (5.2.1.1)
+      actionpack (= 5.2.1.1)
+      actionview (= 5.2.1.1)
+      activejob (= 5.2.1.1)
       mail (~> 2.5, >= 2.5.4)
       rails-dom-testing (~> 2.0)
-    actionpack (5.1.6)
-      actionview (= 5.1.6)
-      activesupport (= 5.1.6)
+    actionpack (5.2.1.1)
+      actionview (= 5.2.1.1)
+      activesupport (= 5.2.1.1)
       rack (~> 2.0)
       rack-test (>= 0.6.3)
       rails-dom-testing (~> 2.0)
       rails-html-sanitizer (~> 1.0, >= 1.0.2)
-    actionview (5.1.6)
-      activesupport (= 5.1.6)
+    actionview (5.2.1.1)
+      activesupport (= 5.2.1.1)
       builder (~> 3.1)
       erubi (~> 1.4)
       rails-dom-testing (~> 2.0)
@@ -39,16 +39,20 @@ GEM
       deprecation (~> 0.1)
       rdf (~> 1.1)
       rdf-vocab (~> 0.8)
-    activejob (5.1.6)
-      activesupport (= 5.1.6)
+    activejob (5.2.1.1)
+      activesupport (= 5.2.1.1)
       globalid (>= 0.3.6)
-    activemodel (5.1.6)
-      activesupport (= 5.1.6)
-    activerecord (5.1.6)
-      activemodel (= 5.1.6)
-      activesupport (= 5.1.6)
-      arel (~> 8.0)
-    activesupport (5.1.6)
+    activemodel (5.2.1.1)
+      activesupport (= 5.2.1.1)
+    activerecord (5.2.1.1)
+      activemodel (= 5.2.1.1)
+      activesupport (= 5.2.1.1)
+      arel (>= 9.0)
+    activestorage (5.2.1.1)
+      actionpack (= 5.2.1.1)
+      activerecord (= 5.2.1.1)
+      marcel (~> 0.3.1)
+    activesupport (5.2.1.1)
       concurrent-ruby (~> 1.0, >= 1.0.2)
       i18n (>= 0.7, < 2)
       minitest (~> 5.1)
@@ -57,7 +61,7 @@ GEM
       public_suffix (>= 2.0.2, < 4.0)
     airbrussh (1.3.1)
       sshkit (>= 1.6.1, != 1.7.0)
-    arel (8.0.0)
+    arel (9.0.0)
     ast (2.4.0)
     builder (3.2.3)
     bundler-audit (0.6.0)
@@ -218,10 +222,13 @@ GEM
     marc (1.0.2)
       scrub_rb (>= 1.0.1, < 2)
       unf
+    marcel (0.3.3)
+      mimemagic (~> 0.3.2)
     method_source (0.9.2)
     mime-types (3.2.2)
       mime-types-data (~> 3.2015)
     mime-types-data (3.2018.0812)
+    mimemagic (0.3.2)
     mini_mime (1.0.1)
     mini_portile2 (2.3.0)
     minitest (5.11.3)
@@ -271,17 +278,18 @@ GEM
       rack-test
     rack-test (1.1.0)
       rack (>= 1.0, < 3)
-    rails (5.1.6)
-      actioncable (= 5.1.6)
-      actionmailer (= 5.1.6)
-      actionpack (= 5.1.6)
-      actionview (= 5.1.6)
-      activejob (= 5.1.6)
-      activemodel (= 5.1.6)
-      activerecord (= 5.1.6)
-      activesupport (= 5.1.6)
+    rails (5.2.1.1)
+      actioncable (= 5.2.1.1)
+      actionmailer (= 5.2.1.1)
+      actionpack (= 5.2.1.1)
+      actionview (= 5.2.1.1)
+      activejob (= 5.2.1.1)
+      activemodel (= 5.2.1.1)
+      activerecord (= 5.2.1.1)
+      activestorage (= 5.2.1.1)
+      activesupport (= 5.2.1.1)
       bundler (>= 1.3.0)
-      railties (= 5.1.6)
+      railties (= 5.2.1.1)
       sprockets-rails (>= 2.0.0)
     rails-controller-testing (1.0.2)
       actionpack (~> 5.x, >= 5.0.1)
@@ -292,12 +300,12 @@ GEM
       nokogiri (>= 1.6)
     rails-html-sanitizer (1.0.4)
       loofah (~> 2.2, >= 2.2.2)
-    railties (5.1.6)
-      actionpack (= 5.1.6)
-      activesupport (= 5.1.6)
+    railties (5.2.1.1)
+      actionpack (= 5.2.1.1)
+      activesupport (= 5.2.1.1)
       method_source
       rake (>= 0.8.7)
-      thor (>= 0.18.1, < 2.0)
+      thor (>= 0.19.0, < 2.0)
     rainbow (3.0.0)
     rake (12.3.1)
     rb-fsevent (0.10.3)
@@ -424,7 +432,7 @@ GEM
       addressable (>= 2.3.6)
       crack (>= 0.3.2)
       hashdiff
-    websocket-driver (0.6.5)
+    websocket-driver (0.7.0)
       websocket-extensions (>= 0.1.0)
     websocket-extensions (0.1.3)
     workflow-archiver (2.0.3)
@@ -461,7 +469,7 @@ DEPENDENCIES
   okcomputer
   puma (~> 3.0)
   rack-console
-  rails (~> 5.1.0)
+  rails (~> 5.2.0)
   rails-controller-testing
   rest-client
   rspec-rails
diff --git a/config/application.rb b/config/application.rb
index acb5321ec..a8572c944 100644
--- a/config/application.rb
+++ b/config/application.rb
@@ -4,6 +4,8 @@
 # Pick the frameworks you want:
 require "action_controller/railtie"
 
+require_relative 'initializers/monkey_patch_haml4'
+
 # Require the gems listed in Gemfile, including any gems
 # you've limited to :test, :development, or :production.
 Bundler.require(*Rails.groups)
diff --git a/config/initializers/monkey_patch_haml4.rb b/config/initializers/monkey_patch_haml4.rb
new file mode 100644
index 000000000..a630d1ac5
--- /dev/null
+++ b/config/initializers/monkey_patch_haml4.rb
@@ -0,0 +1,7 @@
+# RDF 1.99 requires HAML 4, which depends on ActionView::Template::Handlers::Erubis
+# however, this class is not provided by Rails 5.2.  So we'll provide it here.
+# NOTE: This patch must be in place prior to calling Bundler.require (config/application.rb)
+
+# rubocop:disable Style/ClassAndModuleChildren
+class ActionView::Template::Handlers::Erubis; end
+# rubocop:enable Style/ClassAndModuleChildren