diff --git a/.travis.yml b/.travis.yml
index 2cc33b2..14d2063 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,30 +1,29 @@
 sudo: false
 language: ruby
 rvm:
-  - 2.0.0
-  - 2.1.9
-  - 2.2.5
-  - 2.3.1
+  - 2.1.10
+  - 2.2.6
+  - 2.3.3
+  - 2.4.0
   - ruby-head
 env:
-  - "RAILS_VERSION=4.0"
-  - "RAILS_VERSION=4.1"
-  - "RAILS_VERSION=4.2"
-  - "RAILS_VERSION=5.0"
+  - "RAILS_VERSION=4.1.0"
+  - "RAILS_VERSION=4.2.0"
+  - "RAILS_VERSION=5.0.0"
 matrix:
   allow_failures:
     - rvm: ruby-head
   exclude:
-    - rvm: 2.0.0
-      env: "RAILS_VERSION=5.0"
-    - rvm: 2.1.9
-      env: "RAILS_VERSION=5.0"
+    - rvm: 2.1.10
+      env: "RAILS_VERSION=5.0.0"
+    - rvm: 2.4.0
+      env: "RAILS_VERSION=4.1.0"
+    - rvm: 2.4.0
+      env: "RAILS_VERSION=4.2.0"
     - rvm: ruby-head
-      env: "RAILS_VERSION=4.0"
+      env: "RAILS_VERSION=4.1.0"
     - rvm: ruby-head
-      env: "RAILS_VERSION=4.1"
-    - rvm: ruby-head
-      env: "RAILS_VERSION=4.2"
+      env: "RAILS_VERSION=4.2.0"
 
 bundler_args: "--jobs=3 --retry=3"
 cache: bundler
diff --git a/activerecord-userstamp.gemspec b/activerecord-userstamp.gemspec
index 79bd2d2..adbdc44 100644
--- a/activerecord-userstamp.gemspec
+++ b/activerecord-userstamp.gemspec
@@ -23,17 +23,17 @@ Gem::Specification.new do |s|
     rails_version =
       case ENV['RAILS_VERSION']
       when nil, ''
-        '>= 4.0'
+        '>= 4.1'
       else
         "~> #{ENV['RAILS_VERSION']}"
       end
   else
-    rails_version = '>= 4.0'
+    rails_version = '>= 4.1'
   end
 
   s.add_dependency 'rails', rails_version
 
-  s.add_development_dependency 'tzinfo-data'
+  s.add_development_dependency 'tzinfo-data' if RUBY_PLATFORM =~ /mswin|mingw/
   s.add_development_dependency 'rake'
   s.add_development_dependency 'rdoc'
   s.add_development_dependency 'rspec-rails', '>= 3.3'
diff --git a/spec/dummy/config/application.rb b/spec/dummy/config/application.rb
index b563bdb..6301016 100644
--- a/spec/dummy/config/application.rb
+++ b/spec/dummy/config/application.rb
@@ -19,8 +19,11 @@ class Application < Rails::Application
     # config.i18n.load_path += Dir[Rails.root.join('my', 'locales', '*.{rb,yml}').to_s]
     # config.i18n.default_locale = :de
 
-    # Do not swallow errors in after_commit/after_rollback callbacks.
-    config.active_record.raise_in_transactional_callbacks = true
+    # Do not swallow errors in after_commit/after_rollback callbacks. This only applies to Rails 4.2
+    # and is deprecated in Rail 5.
+    if ActiveRecord.version == Gem::Version.new('4.2.x')
+      config.active_record.raise_in_transactional_callbacks = true
+    end
 
     config.after_initialize do
       require_relative '../db/schema'
diff --git a/spec/lib/stamping_spec.rb b/spec/lib/stamping_spec.rb
index f43220f..f1f3c50 100644
--- a/spec/lib/stamping_spec.rb
+++ b/spec/lib/stamping_spec.rb
@@ -134,7 +134,7 @@
         User.stamper = @hera
         expect(User.stamper).to eq(@hera)
 
-        @delynn.name << " Berry"
+        @delynn.name = @delynn.name + " Berry"
         @delynn.save
         @delynn.reload
         expect(@delynn.creator).to eq(@zeus)
@@ -149,7 +149,7 @@
         User.stamper = @hera.id
         expect(User.stamper).to eq(@hera.id)
 
-        @delynn.name << " Berry"
+        @delynn.name = @delynn.name + " Berry"
         @delynn.save
         @delynn.reload
         expect(@delynn.creator_id).to eq(@zeus.id)
@@ -184,7 +184,7 @@
         Person.stamper = @nicole.id
         expect(Person.stamper).to eq(@nicole.id)
 
-        @first_post.title << " - Updated"
+        @first_post.title = @first_post.title + " - Updated"
         @first_post.save
         @first_post.reload
         expect(@first_post.creator_id).to eq(@delynn.id)
@@ -199,7 +199,7 @@
         Person.stamper = @nicole
         expect(Person.stamper).to eq(@nicole)
 
-        @first_post.title << " - Updated"
+        @first_post.title = @first_post.title + " - Updated"
         @first_post.save
         @first_post.reload
         expect(@first_post.creator_id).to eq(@delynn.id)