diff --git a/lib/active_sorting/model.rb b/lib/active_sorting/model.rb
index 43b383b..bf5a2a6 100644
--- a/lib/active_sorting/model.rb
+++ b/lib/active_sorting/model.rb
@@ -75,7 +75,7 @@ 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)
+        unless active_sorting_step.is_a?(Integer)
           raise ArgumentError, "Sortable step should be of type Fixnum, #{active_sorting_step.class.name} where given"
         end
         unless active_sorting_scope.respond_to?(:each)
diff --git a/lib/active_sorting/version.rb b/lib/active_sorting/version.rb
index ae20cca..67f0a1a 100644
--- a/lib/active_sorting/version.rb
+++ b/lib/active_sorting/version.rb
@@ -1,3 +1,3 @@
 module ActiveSorting
-  VERSION = '0.8.4'.freeze
+  VERSION = '0.8.5'.freeze
 end