diff --git a/app/helpers/maintenance_tasks/tasks_helper.rb b/app/helpers/maintenance_tasks/tasks_helper.rb
index 3d1dc138..afc12180 100644
--- a/app/helpers/maintenance_tasks/tasks_helper.rb
+++ b/app/helpers/maintenance_tasks/tasks_helper.rb
@@ -109,7 +109,7 @@ def parameter_field(form_builder, parameter_name)
       when ActiveModel::Type::Decimal, ActiveModel::Type::Float
         form_builder.number_field(parameter_name, { step: "any" })
       when ActiveModel::Type::DateTime
-        form_builder.datetime_field(parameter_name)
+        form_builder.datetime_field(parameter_name) + datetime_field_help_text
       when ActiveModel::Type::Date
         form_builder.date_field(parameter_name)
       when ActiveModel::Type::Time
@@ -120,5 +120,13 @@ def parameter_field(form_builder, parameter_name)
         form_builder.text_area(parameter_name, class: "textarea")
       end
     end
+
+    # Return helper text for the datetime-local form field.
+    def datetime_field_help_text
+      tag.div(
+        tag.p("Datetime inputs will use the system timezone, which is #{Time.now.zone}."),
+        class: "content is-small",
+      )
+    end
   end
 end