diff --git a/votingapi.admin.inc b/votingapi.admin.inc
index 2fb9d87..e061a3d 100644
--- a/votingapi.admin.inc
+++ b/votingapi.admin.inc
@@ -27,6 +27,17 @@ function votingapi_settings_form($form_state) {
     '#options' => $period
   );

+  $form['votingapi_anonymous_validation_method'] = array(
+    '#type' => 'select',
+    '#title' => t('Anonymous validation method'),
+    '#description' => t('By default, voting api will handle vote validation on unique IP. With this setting, you can choose to validate on the unique session ID.'),
+    '#default_value' => variable_get('votingapi_anonymous_validation_method', 'ip'),
+    '#options' => array(
+      'ip' => t('Normal approach with IP validation'),
+      'session' => t('Session id validation')
+    )
+  );
+
   $form['votingapi_calculation_schedule'] = array(
     '#type' => 'radios',
     '#title' => t('Vote tallying'),
diff --git a/votingapi.module b/votingapi.module
index 4d152fe..19ace0a 100644
--- a/votingapi.module
+++ b/votingapi.module
@@ -187,7 +187,7 @@ function votingapi_current_user_identifier() {
   global $user;
   $criteria = array('uid' => $user->uid);
   if (!$user->uid) {
-    $criteria['vote_source'] = ip_address();
+    $criteria['vote_source'] = variable_get('votingapi_anonymous_validation_method', 'ip') == 'session' ? session_id() : ip_address();
   }
   return $criteria;
 }
@@ -593,7 +593,7 @@ function _votingapi_prep_vote(&$vote) {
       'tag' => 'vote',
       'uid' => $user->uid,
       'timestamp' => REQUEST_TIME,
-      'vote_source' => ip_address(),
+      'vote_source' => (variable_get('votingapi_anonymous_validation_method', 'ip') == 'session' ? session_id() : ip_address()),
       'prepped' => TRUE
     );
   }