diff --git a/.travis.yml b/.travis.yml
index 651e65d..4875d32 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -5,6 +5,7 @@ rvm:
 - 2.1.8
 - 2.0.0
 - rbx-2
+- 2.5.1
 before_install:
   - gem install bundler -v '~> 1.11'
 gemfile:
@@ -20,5 +21,11 @@ matrix:
       gemfile: gemfiles/50.gemfile
     - rvm: rbx-2
       gemfile: gemfiles/50.gemfile
+    - rvm: 2.5.1
+      gemfile: gemfiles/40.gemfile
+    - rvm: 2.5.1
+      gemfile: gemfiles/41.gemfile
+    - rvm: 2.5.1
+      gemfile: gemfiles/42.gemfile
 cache:
   - bundler
diff --git a/gemfiles/40.gemfile.lock b/gemfiles/40.gemfile.lock
index b4f128d..e69de29 100644
--- a/gemfiles/40.gemfile.lock
+++ b/gemfiles/40.gemfile.lock
@@ -1,126 +0,0 @@
-PATH
-  remote: ../
-  specs:
-    activesorting (0.7.1)
-      activerecord (>= 4.0.0)
-      railties (>= 4.0.0)
-
-GEM
-  remote: https://rubygems.org/
-  specs:
-    actionmailer (4.0.13)
-      actionpack (= 4.0.13)
-      mail (~> 2.5, >= 2.5.4)
-    actionpack (4.0.13)
-      activesupport (= 4.0.13)
-      builder (~> 3.1.0)
-      erubis (~> 2.7.0)
-      rack (~> 1.5.2)
-      rack-test (~> 0.6.2)
-    activemodel (4.0.13)
-      activesupport (= 4.0.13)
-      builder (~> 3.1.0)
-    activerecord (4.0.13)
-      activemodel (= 4.0.13)
-      activerecord-deprecated_finders (~> 1.0.2)
-      activesupport (= 4.0.13)
-      arel (~> 4.0.0)
-    activerecord-deprecated_finders (1.0.4)
-    activesupport (4.0.13)
-      i18n (~> 0.6, >= 0.6.9)
-      minitest (~> 4.2)
-      multi_json (~> 1.3)
-      thread_safe (~> 0.1)
-      tzinfo (~> 0.3.37)
-    appraisal (2.1.0)
-      bundler
-      rake
-      thor (>= 0.14.0)
-    arel (4.0.2)
-    builder (3.1.4)
-    concurrent-ruby (1.0.1)
-    coveralls (0.8.13)
-      json (~> 1.8)
-      simplecov (~> 0.11.0)
-      term-ansicolor (~> 1.3)
-      thor (~> 0.19.1)
-      tins (~> 1.6.0)
-    database_cleaner (1.5.1)
-    diff-lcs (1.2.5)
-    docile (1.1.5)
-    erubis (2.7.0)
-    i18n (0.7.0)
-    json (1.8.3)
-    mail (2.6.4)
-      mime-types (>= 1.16, < 4)
-    mime-types (3.0)
-      mime-types-data (~> 3.2015)
-    mime-types-data (3.2016.0221)
-    minitest (4.7.5)
-    multi_json (1.11.2)
-    rack (1.5.5)
-    rack-test (0.6.3)
-      rack (>= 1.0)
-    rails (4.0.13)
-      actionmailer (= 4.0.13)
-      actionpack (= 4.0.13)
-      activerecord (= 4.0.13)
-      activesupport (= 4.0.13)
-      bundler (>= 1.3.0, < 2.0)
-      railties (= 4.0.13)
-      sprockets-rails (~> 2.0)
-    railties (4.0.13)
-      actionpack (= 4.0.13)
-      activesupport (= 4.0.13)
-      rake (>= 0.8.7)
-      thor (>= 0.18.1, < 2.0)
-    rake (10.5.0)
-    rspec (3.4.0)
-      rspec-core (~> 3.4.0)
-      rspec-expectations (~> 3.4.0)
-      rspec-mocks (~> 3.4.0)
-    rspec-core (3.4.4)
-      rspec-support (~> 3.4.0)
-    rspec-expectations (3.4.0)
-      diff-lcs (>= 1.2.0, < 2.0)
-      rspec-support (~> 3.4.0)
-    rspec-mocks (3.4.1)
-      diff-lcs (>= 1.2.0, < 2.0)
-      rspec-support (~> 3.4.0)
-    rspec-support (3.4.1)
-    simplecov (0.11.2)
-      docile (~> 1.1.0)
-      json (~> 1.8)
-      simplecov-html (~> 0.10.0)
-    simplecov-html (0.10.0)
-    sprockets (3.5.2)
-      concurrent-ruby (~> 1.0)
-      rack (> 1, < 3)
-    sprockets-rails (2.3.3)
-      actionpack (>= 3.0)
-      activesupport (>= 3.0)
-      sprockets (>= 2.8, < 4.0)
-    sqlite3 (1.3.11)
-    term-ansicolor (1.3.2)
-      tins (~> 1.0)
-    thor (0.19.1)
-    thread_safe (0.3.5)
-    tins (1.6.0)
-    tzinfo (0.3.48)
-
-PLATFORMS
-  ruby
-
-DEPENDENCIES
-  activesorting!
-  appraisal
-  bundler (~> 1.11)
-  coveralls
-  database_cleaner
-  rails (~> 4.0.0)
-  rake (~> 10.0)
-  rspec
-  sqlite3
-
-BUNDLED WITH
-   1.11.2
diff --git a/gemfiles/41.gemfile.lock b/gemfiles/41.gemfile.lock
index 25762bd..e69de29 100644
--- a/gemfiles/41.gemfile.lock
+++ b/gemfiles/41.gemfile.lock
@@ -1,130 +0,0 @@
-PATH
-  remote: ../
-  specs:
-    activesorting (0.7.1)
-      activerecord (>= 4.0.0)
-      railties (>= 4.0.0)
-
-GEM
-  remote: https://rubygems.org/
-  specs:
-    actionmailer (4.1.15)
-      actionpack (= 4.1.15)
-      actionview (= 4.1.15)
-      mail (~> 2.5, >= 2.5.4)
-    actionpack (4.1.15)
-      actionview (= 4.1.15)
-      activesupport (= 4.1.15)
-      rack (~> 1.5.2)
-      rack-test (~> 0.6.2)
-    actionview (4.1.15)
-      activesupport (= 4.1.15)
-      builder (~> 3.1)
-      erubis (~> 2.7.0)
-    activemodel (4.1.15)
-      activesupport (= 4.1.15)
-      builder (~> 3.1)
-    activerecord (4.1.15)
-      activemodel (= 4.1.15)
-      activesupport (= 4.1.15)
-      arel (~> 5.0.0)
-    activesupport (4.1.15)
-      i18n (~> 0.6, >= 0.6.9)
-      json (~> 1.7, >= 1.7.7)
-      minitest (~> 5.1)
-      thread_safe (~> 0.1)
-      tzinfo (~> 1.1)
-    appraisal (2.1.0)
-      bundler
-      rake
-      thor (>= 0.14.0)
-    arel (5.0.1.20140414130214)
-    builder (3.2.2)
-    concurrent-ruby (1.0.1)
-    coveralls (0.8.13)
-      json (~> 1.8)
-      simplecov (~> 0.11.0)
-      term-ansicolor (~> 1.3)
-      thor (~> 0.19.1)
-      tins (~> 1.6.0)
-    database_cleaner (1.5.1)
-    diff-lcs (1.2.5)
-    docile (1.1.5)
-    erubis (2.7.0)
-    i18n (0.7.0)
-    json (1.8.3)
-    mail (2.6.4)
-      mime-types (>= 1.16, < 4)
-    mime-types (3.0)
-      mime-types-data (~> 3.2015)
-    mime-types-data (3.2016.0221)
-    minitest (5.8.4)
-    rack (1.5.5)
-    rack-test (0.6.3)
-      rack (>= 1.0)
-    rails (4.1.15)
-      actionmailer (= 4.1.15)
-      actionpack (= 4.1.15)
-      actionview (= 4.1.15)
-      activemodel (= 4.1.15)
-      activerecord (= 4.1.15)
-      activesupport (= 4.1.15)
-      bundler (>= 1.3.0, < 2.0)
-      railties (= 4.1.15)
-      sprockets-rails (~> 2.0)
-    railties (4.1.15)
-      actionpack (= 4.1.15)
-      activesupport (= 4.1.15)
-      rake (>= 0.8.7)
-      thor (>= 0.18.1, < 2.0)
-    rake (10.5.0)
-    rspec (3.4.0)
-      rspec-core (~> 3.4.0)
-      rspec-expectations (~> 3.4.0)
-      rspec-mocks (~> 3.4.0)
-    rspec-core (3.4.4)
-      rspec-support (~> 3.4.0)
-    rspec-expectations (3.4.0)
-      diff-lcs (>= 1.2.0, < 2.0)
-      rspec-support (~> 3.4.0)
-    rspec-mocks (3.4.1)
-      diff-lcs (>= 1.2.0, < 2.0)
-      rspec-support (~> 3.4.0)
-    rspec-support (3.4.1)
-    simplecov (0.11.2)
-      docile (~> 1.1.0)
-      json (~> 1.8)
-      simplecov-html (~> 0.10.0)
-    simplecov-html (0.10.0)
-    sprockets (3.5.2)
-      concurrent-ruby (~> 1.0)
-      rack (> 1, < 3)
-    sprockets-rails (2.3.3)
-      actionpack (>= 3.0)
-      activesupport (>= 3.0)
-      sprockets (>= 2.8, < 4.0)
-    sqlite3 (1.3.11)
-    term-ansicolor (1.3.2)
-      tins (~> 1.0)
-    thor (0.19.1)
-    thread_safe (0.3.5)
-    tins (1.6.0)
-    tzinfo (1.2.2)
-      thread_safe (~> 0.1)
-
-PLATFORMS
-  ruby
-
-DEPENDENCIES
-  activesorting!
-  appraisal
-  bundler (~> 1.11)
-  coveralls
-  database_cleaner
-  rails (~> 4.1.0)
-  rake (~> 10.0)
-  rspec
-  sqlite3
-
-BUNDLED WITH
-   1.11.2
diff --git a/gemfiles/42.gemfile.lock b/gemfiles/42.gemfile.lock
index b2f42ef..e69de29 100644
--- a/gemfiles/42.gemfile.lock
+++ b/gemfiles/42.gemfile.lock
@@ -1,155 +0,0 @@
-PATH
-  remote: ../
-  specs:
-    activesorting (0.7.1)
-      activerecord (>= 4.0.0)
-      railties (>= 4.0.0)
-
-GEM
-  remote: https://rubygems.org/
-  specs:
-    actionmailer (4.2.6)
-      actionpack (= 4.2.6)
-      actionview (= 4.2.6)
-      activejob (= 4.2.6)
-      mail (~> 2.5, >= 2.5.4)
-      rails-dom-testing (~> 1.0, >= 1.0.5)
-    actionpack (4.2.6)
-      actionview (= 4.2.6)
-      activesupport (= 4.2.6)
-      rack (~> 1.6)
-      rack-test (~> 0.6.2)
-      rails-dom-testing (~> 1.0, >= 1.0.5)
-      rails-html-sanitizer (~> 1.0, >= 1.0.2)
-    actionview (4.2.6)
-      activesupport (= 4.2.6)
-      builder (~> 3.1)
-      erubis (~> 2.7.0)
-      rails-dom-testing (~> 1.0, >= 1.0.5)
-      rails-html-sanitizer (~> 1.0, >= 1.0.2)
-    activejob (4.2.6)
-      activesupport (= 4.2.6)
-      globalid (>= 0.3.0)
-    activemodel (4.2.6)
-      activesupport (= 4.2.6)
-      builder (~> 3.1)
-    activerecord (4.2.6)
-      activemodel (= 4.2.6)
-      activesupport (= 4.2.6)
-      arel (~> 6.0)
-    activesupport (4.2.6)
-      i18n (~> 0.7)
-      json (~> 1.7, >= 1.7.7)
-      minitest (~> 5.1)
-      thread_safe (~> 0.3, >= 0.3.4)
-      tzinfo (~> 1.1)
-    appraisal (2.1.0)
-      bundler
-      rake
-      thor (>= 0.14.0)
-    arel (6.0.3)
-    builder (3.2.2)
-    concurrent-ruby (1.0.1)
-    coveralls (0.8.13)
-      json (~> 1.8)
-      simplecov (~> 0.11.0)
-      term-ansicolor (~> 1.3)
-      thor (~> 0.19.1)
-      tins (~> 1.6.0)
-    database_cleaner (1.5.1)
-    diff-lcs (1.2.5)
-    docile (1.1.5)
-    erubis (2.7.0)
-    globalid (0.3.6)
-      activesupport (>= 4.1.0)
-    i18n (0.7.0)
-    json (1.8.3)
-    loofah (2.0.3)
-      nokogiri (>= 1.5.9)
-    mail (2.6.4)
-      mime-types (>= 1.16, < 4)
-    mime-types (3.0)
-      mime-types-data (~> 3.2015)
-    mime-types-data (3.2016.0221)
-    mini_portile2 (2.0.0)
-    minitest (5.8.4)
-    nokogiri (1.6.7.2)
-      mini_portile2 (~> 2.0.0.rc2)
-    rack (1.6.4)
-    rack-test (0.6.3)
-      rack (>= 1.0)
-    rails (4.2.6)
-      actionmailer (= 4.2.6)
-      actionpack (= 4.2.6)
-      actionview (= 4.2.6)
-      activejob (= 4.2.6)
-      activemodel (= 4.2.6)
-      activerecord (= 4.2.6)
-      activesupport (= 4.2.6)
-      bundler (>= 1.3.0, < 2.0)
-      railties (= 4.2.6)
-      sprockets-rails
-    rails-deprecated_sanitizer (1.0.3)
-      activesupport (>= 4.2.0.alpha)
-    rails-dom-testing (1.0.7)
-      activesupport (>= 4.2.0.beta, < 5.0)
-      nokogiri (~> 1.6.0)
-      rails-deprecated_sanitizer (>= 1.0.1)
-    rails-html-sanitizer (1.0.3)
-      loofah (~> 2.0)
-    railties (4.2.6)
-      actionpack (= 4.2.6)
-      activesupport (= 4.2.6)
-      rake (>= 0.8.7)
-      thor (>= 0.18.1, < 2.0)
-    rake (10.5.0)
-    rspec (3.4.0)
-      rspec-core (~> 3.4.0)
-      rspec-expectations (~> 3.4.0)
-      rspec-mocks (~> 3.4.0)
-    rspec-core (3.4.4)
-      rspec-support (~> 3.4.0)
-    rspec-expectations (3.4.0)
-      diff-lcs (>= 1.2.0, < 2.0)
-      rspec-support (~> 3.4.0)
-    rspec-mocks (3.4.1)
-      diff-lcs (>= 1.2.0, < 2.0)
-      rspec-support (~> 3.4.0)
-    rspec-support (3.4.1)
-    simplecov (0.11.2)
-      docile (~> 1.1.0)
-      json (~> 1.8)
-      simplecov-html (~> 0.10.0)
-    simplecov-html (0.10.0)
-    sprockets (3.5.2)
-      concurrent-ruby (~> 1.0)
-      rack (> 1, < 3)
-    sprockets-rails (3.0.4)
-      actionpack (>= 4.0)
-      activesupport (>= 4.0)
-      sprockets (>= 3.0.0)
-    sqlite3 (1.3.11)
-    term-ansicolor (1.3.2)
-      tins (~> 1.0)
-    thor (0.19.1)
-    thread_safe (0.3.5)
-    tins (1.6.0)
-    tzinfo (1.2.2)
-      thread_safe (~> 0.1)
-
-PLATFORMS
-  ruby
-
-DEPENDENCIES
-  activesorting!
-  appraisal
-  bundler (~> 1.11)
-  coveralls
-  database_cleaner
-  rails (~> 4.2.0)
-  rake (~> 10.0)
-  rspec
-  sqlite3
-
-BUNDLED WITH
-   1.11.2
diff --git a/gemfiles/50.gemfile.lock b/gemfiles/50.gemfile.lock
index b1bf016..e69de29 100644
--- a/gemfiles/50.gemfile.lock
+++ b/gemfiles/50.gemfile.lock
@@ -1,165 +0,0 @@
-PATH
-  remote: ../
-  specs:
-    activesorting (0.7.1)
-      activerecord (>= 4.0.0)
-      railties (>= 4.0.0)
-
-GEM
-  remote: https://rubygems.org/
-  specs:
-    actioncable (5.0.0.beta3)
-      actionpack (= 5.0.0.beta3)
-      nio4r (~> 1.2)
-      websocket-driver (~> 0.6.1)
-    actionmailer (5.0.0.beta3)
-      actionpack (= 5.0.0.beta3)
-      actionview (= 5.0.0.beta3)
-      activejob (= 5.0.0.beta3)
-      mail (~> 2.5, >= 2.5.4)
-      rails-dom-testing (~> 1.0, >= 1.0.5)
-    actionpack (5.0.0.beta3)
-      actionview (= 5.0.0.beta3)
-      activesupport (= 5.0.0.beta3)
-      rack (~> 2.x)
-      rack-test (~> 0.6.3)
-      rails-dom-testing (~> 1.0, >= 1.0.5)
-      rails-html-sanitizer (~> 1.0, >= 1.0.2)
-    actionview (5.0.0.beta3)
-      activesupport (= 5.0.0.beta3)
-      builder (~> 3.1)
-      erubis (~> 2.7.0)
-      rails-dom-testing (~> 1.0, >= 1.0.5)
-      rails-html-sanitizer (~> 1.0, >= 1.0.2)
-    activejob (5.0.0.beta3)
-      activesupport (= 5.0.0.beta3)
-      globalid (>= 0.3.6)
-    activemodel (5.0.0.beta3)
-      activesupport (= 5.0.0.beta3)
-    activerecord (5.0.0.beta3)
-      activemodel (= 5.0.0.beta3)
-      activesupport (= 5.0.0.beta3)
-      arel (~> 7.0)
-    activesupport (5.0.0.beta3)
-      concurrent-ruby (~> 1.0)
-      i18n (~> 0.7)
-      minitest (~> 5.1)
-      tzinfo (~> 1.1)
-    appraisal (2.1.0)
-      bundler
-      rake
-      thor (>= 0.14.0)
-    arel (7.0.0)
-    builder (3.2.2)
-    concurrent-ruby (1.0.1)
-    coveralls (0.8.13)
-      json (~> 1.8)
-      simplecov (~> 0.11.0)
-      term-ansicolor (~> 1.3)
-      thor (~> 0.19.1)
-      tins (~> 1.6.0)
-    database_cleaner (1.5.1)
-    diff-lcs (1.2.5)
-    docile (1.1.5)
-    erubis (2.7.0)
-    globalid (0.3.6)
-      activesupport (>= 4.1.0)
-    i18n (0.7.0)
-    json (1.8.3)
-    loofah (2.0.3)
-      nokogiri (>= 1.5.9)
-    mail (2.6.4)
-      mime-types (>= 1.16, < 4)
-    method_source (0.8.2)
-    mime-types (3.0)
-      mime-types-data (~> 3.2015)
-    mime-types-data (3.2016.0221)
-    mini_portile2 (2.0.0)
-    minitest (5.8.4)
-    nio4r (1.2.1)
-    nokogiri (1.6.7.2)
-      mini_portile2 (~> 2.0.0.rc2)
-    rack (2.0.0.alpha)
-      json
-    rack-test (0.6.3)
-      rack (>= 1.0)
-    rails (5.0.0.beta3)
-      actioncable (= 5.0.0.beta3)
-      actionmailer (= 5.0.0.beta3)
-      actionpack (= 5.0.0.beta3)
-      actionview (= 5.0.0.beta3)
-      activejob (= 5.0.0.beta3)
-      activemodel (= 5.0.0.beta3)
-      activerecord (= 5.0.0.beta3)
-      activesupport (= 5.0.0.beta3)
-      bundler (>= 1.3.0, < 2.0)
-      railties (= 5.0.0.beta3)
-      sprockets-rails (>= 2.0.0)
-    rails-deprecated_sanitizer (1.0.3)
-      activesupport (>= 4.2.0.alpha)
-    rails-dom-testing (1.0.7)
-      activesupport (>= 4.2.0.beta, < 5.0)
-      nokogiri (~> 1.6.0)
-      rails-deprecated_sanitizer (>= 1.0.1)
-    rails-html-sanitizer (1.0.3)
-      loofah (~> 2.0)
-    railties (5.0.0.beta3)
-      actionpack (= 5.0.0.beta3)
-      activesupport (= 5.0.0.beta3)
-      method_source
-      rake (>= 0.8.7)
-      thor (>= 0.18.1, < 2.0)
-    rake (10.5.0)
-    rspec (3.4.0)
-      rspec-core (~> 3.4.0)
-      rspec-expectations (~> 3.4.0)
-      rspec-mocks (~> 3.4.0)
-    rspec-core (3.4.4)
-      rspec-support (~> 3.4.0)
-    rspec-expectations (3.4.0)
-      diff-lcs (>= 1.2.0, < 2.0)
-      rspec-support (~> 3.4.0)
-    rspec-mocks (3.4.1)
-      diff-lcs (>= 1.2.0, < 2.0)
-      rspec-support (~> 3.4.0)
-    rspec-support (3.4.1)
-    simplecov (0.11.2)
-      docile (~> 1.1.0)
-      json (~> 1.8)
-      simplecov-html (~> 0.10.0)
-    simplecov-html (0.10.0)
-    sprockets (3.5.2)
-      concurrent-ruby (~> 1.0)
-      rack (> 1, < 3)
-    sprockets-rails (3.0.4)
-      actionpack (>= 4.0)
-      activesupport (>= 4.0)
-      sprockets (>= 3.0.0)
-    sqlite3 (1.3.11)
-    term-ansicolor (1.3.2)
-      tins (~> 1.0)
-    thor (0.19.1)
-    thread_safe (0.3.5)
-    tins (1.6.0)
-    tzinfo (1.2.2)
-      thread_safe (~> 0.1)
-    websocket-driver (0.6.3)
-      websocket-extensions (>= 0.1.0)
-    websocket-extensions (0.1.2)
-
-PLATFORMS
-  ruby
-
-DEPENDENCIES
-  activesorting!
-  appraisal
-  bundler (~> 1.11)
-  coveralls
-  database_cleaner
-  rails (= 5.0.0.beta3)
-  rake (~> 10.0)
-  rspec
-  sqlite3
-
-BUNDLED WITH
-   1.11.2
diff --git a/lib/active_sorting/model.rb b/lib/active_sorting/model.rb
index 43b383b..d8e58a9 100644
--- a/lib/active_sorting/model.rb
+++ b/lib/active_sorting/model.rb
@@ -75,8 +75,8 @@ def active_sorting_check_options
         # unless field_type == :integer
         #   raise ArgumentError, "Sortable field should be of type Integer, #{field_type} where given"
         # end
-        unless active_sorting_step.is_a?(Fixnum)
-          raise ArgumentError, "Sortable step should be of type Fixnum, #{active_sorting_step.class.name} where given"
+        unless active_sorting_step.is_a?(Integer)
+          raise ArgumentError, "Sortable step should be of type Integer, #{active_sorting_step.class.name} where given"
         end
         unless active_sorting_scope.respond_to?(:each)
           raise ArgumentError, "Sortable step should be of type Enumerable, #{active_sorting_scope.class.name} where given"