diff --git a/link.inc b/link.inc
index e0ac19d..b9dc352 100644
--- a/link.inc
+++ b/link.inc
@@ -82,7 +82,7 @@ function _link_sanitize(&$item, $delta, &$field, &$node) {
   $type = link_validate_url($item['url']);
   // If we can't determine the type of url, and we've been told not to validate it,
   // then we assume it's a LINK_EXTERNAL type for later processing. #357604
-  if ($type == FALSE && $field['validate_url'] === 0) {
+  if ($type == FALSE && isset($field['validate_url']) && $field['validate_url'] === 0) {
     $type = LINK_EXTERNAL;
   }
   $url = link_cleanup_url($item['url']);
@@ -98,7 +98,7 @@ function _link_sanitize(&$item, $delta, &$field, &$node) {
     $url = substr($url, 0, strpos($url, '?'));
   }
   // Save the new URL without the anchor or query.
-  if ($field['validate_url'] === 0) {
+  if (isset($field['validate_url']) && $field['validate_url'] === 0) {
     $item['url'] = check_plain($url);
   }
   else {
diff --git a/link.module b/link.module
index 2c57c82..34b40ce 100644
--- a/link.module
+++ b/link.module
@@ -63,7 +63,7 @@ function link_field_settings($op, $field) {
       $form['validate_url'] = array(
         '#type' => 'checkbox',
         '#title' => t('Validate URL'),
-        '#default_value' => isset($field['validate_url']) && ($field['validate_url'] !== '') ? $field['validate_url'] : TRUE,
+        '#default_value' => (isset($field['validate_url']) && $field['validate_url'] !== '') ? $field['validate_url'] : TRUE,
         '#description' => t('If checked, the URL field will be verified as a valid URL during validation.'),
       );
 
@@ -212,7 +212,7 @@ function link_field($op, &$node, $field, &$items, $teaser, $page) {
 
     case 'validate':
       $optional_field_found = FALSE;
-      if ($field['validate_url'] !== 0 || is_null($field['validate_url']) || !isset($field['validate_url'])) {
+      if (!isset($field['validate_url']) || $field['validate_url'] !== 0) {
         foreach ($items as $delta => $value) {
           _link_validate($items[$delta], $delta, $field, $node, $optional_field_found);
         }