diff -u b/views_distinct.install b/views_distinct.install
--- b/views_distinct.install
+++ b/views_distinct.install
@@ -18,20 +18,21 @@
 /**
  * Migrate existing views_distinct settings to the variable storage.
  */
-function views_distinct_update_7001() {
-  $result = db_select('views_distinct', 'v')
-    ->fields('v')
-    ->execute();
+function views_distinct_update_7100() {
+  if (db_table_exists('views_distinct')) {
+    $result = db_select('views_distinct', 'v')
+      ->fields('v')
+      ->execute();
 
-  foreach ($result as $v) {
-    $views[$v->view_name][$v->display_id][$v->field_id] = unserialize($v->settings);
-  }
+    $views = array();
+    foreach ($result as $v) {
+      $views[$v->view_name][$v->display_id][$v->field_id] = unserialize($v->settings);
+    }
 
-  foreach ($views as $view_name => $settings) {
-    variable_set('views_distinct:' . $view_name, $settings);
-  }
+    foreach ($views as $view_name => $settings) {
+      variable_set('views_distinct:' . $view_name, $settings);
+    }
 
-  if (db_table_exists('views_distinct')) {
     db_drop_table('views_distinct');
   }
 }
diff -u b/views_distinct.module b/views_distinct.module
--- b/views_distinct.module
+++ b/views_distinct.module
@@ -405,37 +405,37 @@
     $settings = (array) $settings + _views_distinct_field_settings_defaults();
 
     $view_settings = variable_get('views_distinct:'.$view_name);
-    if($view_settings == NULL) {
+    if ($view_settings == NULL) {
       $view_settings = array($display_name => array($field_name => $settings));
     }
-    elseif(isset($view_settings[$display_name])) {
+    elseif (isset($view_settings[$display_name])) {
       $view_settings[$display_name][$field_name] = $settings;
     }
     else {
       $view_settings[$display_name] = array($field_name => $settings);
     }
-    variable_set('views_distinct:'.$view_name, $view_settings);
+    variable_set('views_distinct:' . $view_name, $view_settings);
   }
   else {
     // If we're removing settings, revert the static cache to defaults:
     $settings = _views_distinct_field_settings_defaults();
 
-    //remove field, and display if no more settings
+    // Remove field, and display if no more settings.
     $view_settings = variable_get('views_distinct:'.$view_name);
-    if(isset($view_settings[$display_name][$field_name])) {
+    if (isset($view_settings[$display_name][$field_name])) {
       unset($view_settings[$display_name][$field_name]);
-      if(count($view_settings[$display_name]) == 0) {
+      if (count($view_settings[$display_name]) == 0) {
         unset($view_settings[$display_name]);
       }
     }
 
-    if($view_settings != NULL && count($view_settings) == 0) {
-      //delete variable if no more useful information
-      variable_del('views_distinct:'.$view_name);
+    if ($view_settings != NULL && count($view_settings) == 0) {
+      // Delete variable if no more useful information.
+      variable_del('views_distinct:' . $view_name);
     }
     else {
-      //update just to remove the settings
-      variable_set('views_distinct:'.$view_name, $view_settings);
+      // Update just to remove the settings.
+      variable_set('views_distinct:' . $view_name, $view_settings);
     }
   }