diff --git a/oauth_common.consumers.inc b/oauth_common.consumers.inc
index 073a680..52ddf29 100644
--- a/oauth_common.consumers.inc
+++ b/oauth_common.consumers.inc
@@ -103,6 +103,7 @@ function oauth_common_form_consumer(&$form_state, $consumer) {
     '#title' => t('Callback url'),
     '#required' => FALSE,
     '#default_value' => $consumer->callback_url,
+    '#description' => t('You must include a schema for this to work correctly, ie. http:// or iphoneappname://'),
   );
 
   if ($consumer->in_database) {
@@ -164,6 +165,16 @@ function oauth_common_form_consumer(&$form_state, $consumer) {
 }
 
 /**
+ * Validate handler for oauth_common_form_consumer 
+ */
+function oauth_common_form_consumer_validate($form, &$form_state) {
+  $callback = $form_state['values']['callback_url'];
+  if (!parse_url($callback) || strstr($callback, '://') === FALSE) {
+    form_set_error('callback_url', 'You must set a valid URL as a callback - http/https://some-path or custom://some-path');
+  }
+}
+
+/**
  * Submit handler for oauth_common_form_consumer.
  */
 function oauth_common_form_consumer_submit($form, &$form_state) {
@@ -174,14 +185,11 @@ function oauth_common_form_consumer_submit($form, &$form_state) {
   if (empty($values['callback_url'])) {
     $values['callback_url'] = 'oob';
   }
-  // Add scheme if missing, and if the callback_url isn't out of band.
-  else if ($values['callback_url'] != 'oob' && preg_match('/^http:\/\/|https:\/\//', $values['callback_url']) === 0) {
-    //TODO: What about custom callback url:s used by eg iphone-apps? We should allow them - right?
-    $values['callback_url'] = 'http://' . $values['callback_url'];
-  }
 
-  // Remove trailing slash
-  $values['callback_url'] = rtrim($values['callback_url'], '/');
+  if(substr($values['callback_url'], strlen($values['callback_url']) - 2) != '//') {
+   // Remove trailing slash
+   $values['callback_url'] = rtrim($values['callback_url'], '/');
+  }
 
   // Transfer editable attributes to the consumer.
   $names = array('name', 'callback_url', 'context');