diff --git a/Gemfile b/Gemfile
index dc3643b41..4fa62659e 100644
--- a/Gemfile
+++ b/Gemfile
@@ -67,14 +67,13 @@ gem 'deep_cloneable', '~> 2.1.1'
 gem 'digidoc_client', '~> 0.2.1'
 
 # epp + repp client
-# gem 'depp', github: 'domify/depp', ref: '730b264929613033d334a636a29b04a39693b107'
-gem 'depp', path: '/home/martin/projects/depp'
+gem 'depp', github: 'domify/depp', ref: 'd3fdd1d9dfec8277ceed32fd66f3cb6911bcceb5'
 gem 'epp', '~> 1.4.2', github: 'gitlabeu/epp'
 
 group :development do
   # dev tools
-  gem 'spring',                '~> 1.2.0'
-  gem 'spring-commands-rspec', '~> 1.0.2'
+  gem 'spring',                '~> 1.3.3'
+  gem 'spring-commands-rspec', '~> 1.0.4'
   gem 'guard',                 '~> 2.6.1' # run tests automatically
   gem 'guard-rspec',           '~> 4.3.1'
   gem 'guard-rails',           '~> 0.7.0' # run EPP server automatically
diff --git a/Gemfile.lock b/Gemfile.lock
index b6036a612..2b024d289 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -8,6 +8,25 @@ GIT
       activesupport (>= 3.0, < 6.0)
       request_store (~> 1.1.0)
 
+GIT
+  remote: git://github.com/domify/depp.git
+  revision: d3fdd1d9dfec8277ceed32fd66f3cb6911bcceb5
+  ref: d3fdd1d9dfec8277ceed32fd66f3cb6911bcceb5
+  specs:
+    depp (0.0.2)
+      coderay (>= 1.1.0)
+      coffee-rails (>= 4.1.0)
+      countries (>= 0.9.3)
+      epp-xml (>= 0.10.4)
+      figaro (>= 1.1.0)
+      haml-rails (>= 0.9.0)
+      jquery-rails (>= 4.0.3)
+      nokogiri (>= 1.6.6.2)
+      rails (>= 4.2.1)
+      sass-rails (>= 5.0.0)
+      uglifier (>= 2.6.1)
+      uuidtools (>= 2.1.4)
+
 GIT
   remote: git://github.com/gitlabeu/epp.git
   revision: 505c3f2739eb1da918e54111aecfb138a822739d
@@ -27,23 +46,6 @@ GIT
       nokogiri (~> 1.6.0)
       ruby_parser (~> 3.5)
 
-PATH
-  remote: /home/martin/projects/depp
-  specs:
-    depp (0.0.2)
-      coderay (>= 1.1.0)
-      coffee-rails (>= 4.1.0)
-      countries (>= 0.9.3)
-      epp-xml (>= 0.10.4)
-      figaro (>= 1.1.0)
-      haml-rails (>= 0.9.0)
-      jquery-rails (>= 4.0.3)
-      nokogiri (>= 1.6.6.2)
-      rails (>= 4.2.1)
-      sass-rails (>= 5.0.0)
-      uglifier (>= 2.6.1)
-      uuidtools (>= 2.1.4)
-
 GEM
   remote: https://rubygems.org/
   specs:
@@ -441,7 +443,7 @@ GEM
       temple (~> 0.6.9)
       tilt (>= 1.3.3, < 2.1)
     slop (3.6.0)
-    spring (1.2.0)
+    spring (1.3.3)
     spring-commands-rspec (1.0.4)
       spring (>= 0.9.1)
     sprockets (2.12.3)
@@ -567,8 +569,8 @@ DEPENDENCIES
   shoulda-matchers (~> 2.6.1)
   simplecov (~> 0.9.1)
   simpleidn (~> 0.0.5)
-  spring (~> 1.2.0)
-  spring-commands-rspec (~> 1.0.2)
+  spring (~> 1.3.3)
+  spring-commands-rspec (~> 1.0.4)
   therubyracer
   traceroute (~> 0.4.0)
   turbolinks (~> 2.5.3)
diff --git a/db/migrate/20150320132023_create_invoices.rb b/db/migrate/20150320132023_create_invoices.rb
index 9caf0082a..36376f899 100644
--- a/db/migrate/20150320132023_create_invoices.rb
+++ b/db/migrate/20150320132023_create_invoices.rb
@@ -1,7 +1,7 @@
 class CreateInvoices < ActiveRecord::Migration
   def change
     create_table :invoices do |t|
-      t.timestamps
+      t.timestamps null: false
     end
   end
 end
diff --git a/db/schema.rb b/db/schema.rb
index 4945b36fe..5818a0e3e 100644
--- a/db/schema.rb
+++ b/db/schema.rb
@@ -227,8 +227,8 @@ ActiveRecord::Schema.define(version: 20150320132023) do
   add_index "epp_sessions", ["updated_at"], name: "index_epp_sessions_on_updated_at", using: :btree
 
   create_table "invoices", force: :cascade do |t|
-    t.datetime "created_at"
-    t.datetime "updated_at"
+    t.datetime "created_at", null: false
+    t.datetime "updated_at", null: false
   end
 
   create_table "keyrelays", force: :cascade do |t|