diff --git a/lib/datagrid/drivers/abstract_driver.rb b/lib/datagrid/drivers/abstract_driver.rb
index b663558..5b92409 100644
--- a/lib/datagrid/drivers/abstract_driver.rb
+++ b/lib/datagrid/drivers/abstract_driver.rb
@@ -63,7 +63,7 @@ def reverse_order(scope)
         raise NotImplementedError
       end
 
-      def is_timestamp?(scope, field)
+      def timestamp_column?(scope, field)
         normalized_column_type(scope, field) == :timestamp
       end
 
diff --git a/lib/datagrid/drivers/mongo_mapper.rb b/lib/datagrid/drivers/mongo_mapper.rb
index 48871ac..b0a7738 100644
--- a/lib/datagrid/drivers/mongo_mapper.rb
+++ b/lib/datagrid/drivers/mongo_mapper.rb
@@ -46,7 +46,7 @@ def scope_has_column?(scope, column_name)
         scope.key?(column_name)
       end
 
-      def is_timestamp?(_scope, _column_name)
+      def timestamp_column?(_scope, _column_name)
         # TODO: implement the support
         false
       end
diff --git a/lib/datagrid/filters/date_filter.rb b/lib/datagrid/filters/date_filter.rb
index 9793698..c219276 100644
--- a/lib/datagrid/filters/date_filter.rb
+++ b/lib/datagrid/filters/date_filter.rb
@@ -29,7 +29,7 @@ def format(value)
       end
 
       def default_filter_where(scope, value)
-        value = Datagrid::Utils.format_date_as_timestamp(value) if driver.is_timestamp?(scope, name)
+        value = Datagrid::Utils.format_date_as_timestamp(value) if driver.timestamp_column?(scope, name)
         super
       end
 
diff --git a/lib/datagrid/filters/dynamic_filter.rb b/lib/datagrid/filters/dynamic_filter.rb
index 9926ff0..967a37d 100644
--- a/lib/datagrid/filters/dynamic_filter.rb
+++ b/lib/datagrid/filters/dynamic_filter.rb
@@ -42,7 +42,7 @@ def default_filter_where(scope, filter)
         field = filter.field
         operation = filter.operation
         value = filter.value
-        date_conversion = value.is_a?(Date) && driver.is_timestamp?(scope, field)
+        date_conversion = value.is_a?(Date) && driver.timestamp_column?(scope, field)
 
         return scope if field.blank? || operation.blank?
 
diff --git a/lib/datagrid/utils.rb b/lib/datagrid/utils.rb
index f97707d..f0c5d26 100644
--- a/lib/datagrid/utils.rb
+++ b/lib/datagrid/utils.rb
@@ -107,6 +107,7 @@ def parse_datetime(value)
           Array(Datagrid.configuration.datetime_formats).each do |format|
             return Time.strptime(value, format)
           rescue ::ArgumentError
+            nil
           end
         end
         return Time.parse(value) if value.is_a?(String)
diff --git a/spec/datagrid/filters_spec.rb b/spec/datagrid/filters_spec.rb
index 457c75f..67aa8db 100644
--- a/spec/datagrid/filters_spec.rb
+++ b/spec/datagrid/filters_spec.rb
@@ -298,16 +298,16 @@ class TestGrid8728 < Datagrid::Base
     end
 
     context "with delegation to attribute" do
-      let(:role) { Struct.new(:admin?).new(admin) }
+      let(:role) { Struct.new(:admin).new(admin) }
       let(:klass) do
         test_report_class do
           attr_accessor :role
 
-          delegate :admin?, to: :role
+          delegate :admin, to: :role
 
           scope { Entry }
 
-          filter(:id, :integer, if: :admin?)
+          filter(:id, :integer, if: :admin)
         end
       end