diff --git a/.ruby-version b/.ruby-version
new file mode 100644
index 0000000..8e8299d
--- /dev/null
+++ b/.ruby-version
@@ -0,0 +1 @@
+2.4.2
diff --git a/Gemfile.lock b/Gemfile.lock
index f5bb37c..8aa3247 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -86,23 +86,21 @@ GEM
       gemoji (~> 2.0)
       html-pipeline (~> 2.2)
       jekyll (>= 3.0)
-    json (1.8.3)
+    json (1.8.6)
     kramdown (1.11.1)
     liquid (3.0.6)
     listen (3.0.6)
       rb-fsevent (>= 0.9.3)
       rb-inotify (>= 0.9.7)
     mercenary (0.3.6)
-    mini_portile2 (2.1.0)
+    mini_portile2 (2.3.0)
     minitest (5.9.0)
     multipart-post (2.0.0)
     net-dns (0.8.0)
-    nokogiri (1.6.8)
-      mini_portile2 (~> 2.1.0)
-      pkg-config (~> 1.1.7)
+    nokogiri (1.8.2)
+      mini_portile2 (~> 2.3.0)
     octokit (4.3.0)
       sawyer (~> 0.7.0, >= 0.5.3)
-    pkg-config (1.1.7)
     public_suffix (1.5.3)
     rb-fsevent (0.9.7)
     rb-inotify (0.9.7)
@@ -127,4 +125,4 @@ DEPENDENCIES
   github-pages
 
 BUNDLED WITH
-   1.12.5
+   1.16.0