diff --git a/Gemfile b/Gemfile
index 282d3ed..c9c4f61 100644
--- a/Gemfile
+++ b/Gemfile
@@ -8,3 +8,4 @@ source "https://rubygems.org"
 
 gem "scraperwiki", git: "https://github.com/openaustralia/scraperwiki-ruby.git", branch: "morph_defaults"
 gem "mechanize"
+gem "activesupport" # For date calculations
diff --git a/Gemfile.lock b/Gemfile.lock
index 05a919e..7a49ced 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -10,11 +10,18 @@ GIT
 GEM
   remote: https://rubygems.org/
   specs:
+    activesupport (5.1.2)
+      concurrent-ruby (~> 1.0, >= 1.0.2)
+      i18n (~> 0.7)
+      minitest (~> 5.1)
+      tzinfo (~> 1.1)
+    concurrent-ruby (1.0.5)
     domain_name (0.5.20170404)
       unf (>= 0.0.5, < 1.0.0)
     http-cookie (1.0.3)
       domain_name (~> 0.5)
     httpclient (2.8.3)
+    i18n (0.8.4)
     mechanize (2.7.5)
       domain_name (~> 0.5, >= 0.5.1)
       http-cookie (~> 1.0)
@@ -28,6 +35,7 @@ GEM
       mime-types-data (~> 3.2015)
     mime-types-data (3.2016.0521)
     mini_portile2 (2.2.0)
+    minitest (5.10.2)
     net-http-digest_auth (1.4.1)
     net-http-persistent (2.9.4)
     nokogiri (1.8.0)
@@ -36,6 +44,9 @@ GEM
     sqlite3 (1.3.13)
     sqlite_magic (0.0.6)
       sqlite3
+    thread_safe (0.3.6)
+    tzinfo (1.2.3)
+      thread_safe (~> 0.1)
     unf (0.1.4)
       unf_ext
     unf_ext (0.0.7.4)
@@ -45,6 +56,7 @@ PLATFORMS
   ruby
 
 DEPENDENCIES
+  activesupport
   mechanize
   scraperwiki!