diff --git a/date.field.inc b/date.field.inc
index 08d89d4..c32ebe4 100644
--- a/date.field.inc
+++ b/date.field.inc
@@ -463,6 +463,14 @@ function date_field_instance_settings_form($field, $instance) {
 }
 
 /**
+ * Form validation handler for _date_field_instance_settings_form().
+ */
+function date_field_instance_settings_form_validate(&$form, &$form_state) {
+  module_load_include('inc', 'date', 'date_admin');
+  return _date_field_instance_settings_form_validate($form, $form_state);
+}
+
+/**
  * Implements hook_field_widget_settings_form().
  */
 function date_field_widget_settings_form($field, $instance) {
@@ -471,6 +479,14 @@ function date_field_widget_settings_form($field, $instance) {
 }
 
 /**
+ * Form validation handler for _date_field_widget_settings_form().
+ */
+function date_field_widget_settings_form_validate(&$form, &$form_state) {
+  module_load_include('inc', 'date', 'date_admin');
+  return _date_field_widget_settings_form_validate($form, $form_state);
+}
+
+/**
  * Implements hook_field_settings_form().
  */
 function date_field_settings_form($field, $instance, $has_data) {
@@ -479,6 +495,14 @@ function date_field_settings_form($field, $instance, $has_data) {
 }
 
 /**
+ * Form validation handler for _date_field_settings_form().
+ */
+function date_field_settings_validate(&$form, &$form_state) {
+  module_load_include('inc', 'date', 'date_admin');
+  return _date_field_settings_validate($form, $form_state);
+}
+
+/**
  * Implements hook_content_migrate_field_alter().
  *
  * Use this to tweak the conversion of field settings from the D6 style to the
diff --git a/date_admin.inc b/date_admin.inc
index 13da42e..a87e52f 100644
--- a/date_admin.inc
+++ b/date_admin.inc
@@ -273,7 +273,7 @@ function _date_field_instance_settings_form($field, $instance) {
 /**
  * Form validation handler for _date_field_instance_settings_form().
  */
-function date_field_instance_settings_form_validate(&$form, &$form_state) {
+function _date_field_instance_settings_form_validate(&$form, &$form_state) {
   $settings = $form_state['values']['instance']['settings'];
 
   if ($settings['default_value'] == 'strtotime') {
@@ -459,7 +459,7 @@ function _date_field_widget_settings_form($field, $instance) {
 /**
  * Form validation handler for _date_field_widget_settings_form().
  */
-function date_field_widget_settings_form_validate(&$form, &$form_state) {
+function _date_field_widget_settings_form_validate(&$form, &$form_state) {
   // The widget settings are in the wrong place in the form because of #tree on
   // the top level.
   $settings = $form_state['values']['instance']['widget']['settings'];
@@ -594,7 +594,7 @@ function _date_field_settings_form($field, $instance, $has_data) {
 /**
  * Form validation handler for _date_field_settings_form().
  */
-function date_field_settings_validate(&$form, &$form_state) {
+function _date_field_settings_validate(&$form, &$form_state) {
   $field = &$form_state['values']['field'];
 
   if ($field['settings']['tz_handling'] == 'none') {