diff --git a/remarkable_datamapper/lib/remarkable_datamapper/matchers/validate_is_unique_matcher.rb b/remarkable_datamapper/lib/remarkable_datamapper/matchers/validate_is_unique_matcher.rb
index de9d7bd..9e88af9 100644
--- a/remarkable_datamapper/lib/remarkable_datamapper/matchers/validate_is_unique_matcher.rb
+++ b/remarkable_datamapper/lib/remarkable_datamapper/matchers/validate_is_unique_matcher.rb
@@ -112,7 +112,7 @@ def new_value_for_scope(scope)
               nil
             end
 
-            case column_type.type
+            case column_type.class
               when :int, :integer, :float, :decimal
                 new_value_for_stringfiable_scope(scope)
               when :datetime, :timestamp, :time