Trouble with the mysql2 version

Gemfile

@@ -128,5 +128,5 @@ end
 
 group :production do
   # Use mysql as the database for Active Record
-  gem 'mysql2'
+	gem 'mysql2', '~> 0.3.18'
 end

Gemfile.lock

@@ -263,7 +263,7 @@ GEM
     modernizr-rails (2.7.1)
     multi_json (1.11.2)
     multipart-post (2.0.0)
-    mysql2 (0.4.0)
+    mysql2 (0.3.20)
     naught (1.1.0)
     nenv (0.2.0)
     nokogiri (1.6.6.2)
@@ -428,7 +428,7 @@ GEM
       railties (>= 4.0)
       sprockets-rails (>= 2.0, < 4.0)
     webrick (1.3.1)
-    webshims-rails (1.15.8)
+    webshims-rails (1.15.9)
       rails (> 3.1.0)
 
 PLATFORMS
@@ -467,7 +467,7 @@ DEPENDENCIES
   leaflet-rails
   meta-tags
   modernizr-rails
-  mysql2
+  mysql2 (~> 0.3.18)
   paper_trail (~> 4.0.0.rc)
   quiet_assets
   rails