diff --git a/core/lib/Drupal/Core/Database/Query/Condition.php b/core/lib/Drupal/Core/Database/Query/Condition.php
index 00e9015..1c91d9b 100644
--- a/core/lib/Drupal/Core/Database/Query/Condition.php
+++ b/core/lib/Drupal/Core/Database/Query/Condition.php
@@ -245,22 +245,21 @@ public function compile(Connection $connection, PlaceholderInterface $queryPlace
           // For simplicity, we first convert to an array, so that we can handle
           // the single and multi value cases the same.
           if (!is_array($condition['value'])) {
-            if ($operator['operator'] == 'IN' && $condition['value'] instanceof ConditionInterface) {
-              // Special case: IN is followed by a select query instead of a set
-              // of values: unset prefix and postfix to prevent double brackets.
+            if ($condition['value'] instanceof SelectInterface && ($operator['operator'] === 'IN' || $operator['operator'] === 'NOT IN')) {
+              // Special case: IN is followed by a single select query instead
+              // of a set of values: unset prefix and postfix to prevent double
+              // brackets.
               $operator['prefix'] = '';
               $operator['postfix'] = '';
-
             }
-
             $condition['value'] = array($condition['value']);
           }
           // Process all individual values.
           $value_fragment = array();
           foreach ($condition['value'] as $value) {
-            if ($value instanceof ConditionInterface) {
-              // Right hand part is a subquery. Compile, assure that brackets
-              // are put around it and collect any arguments.
+            if ($value instanceof SelectInterface) {
+              // Right hand part is a subquery. Compile, put brackets around it
+              // and collect any arguments.
               $value->compile($connection, $queryPlaceholder);
               $value_fragment[] = '(' . (string) $value . ')';
               $arguments += $value->arguments();
@@ -347,15 +346,18 @@ protected function mapConditionOperator($operator) {
     // $specials does not use drupal_static as its value never changes.
     static $specials = array(
       'BETWEEN' => array('delimiter' => ' AND '),
+      'NOT BETWEEN' => array('delimiter' => ' AND '),
       'IN' => array('delimiter' => ', ', 'prefix' => '(', 'postfix' => ')'),
       'NOT IN' => array('delimiter' => ', ', 'prefix' => '(', 'postfix' => ')'),
-      'EXISTS' => array('prefix' => '(', 'postfix' => ')'),
-      'NOT EXISTS' => array('prefix' => '(', 'postfix' => ')'),
       'IS NULL' => array('use_value' => FALSE),
       'IS NOT NULL' => array('use_value' => FALSE),
       // Use backslash for escaping wildcard characters.
       'LIKE' => array('postfix' => " ESCAPE '\\\\'"),
       'NOT LIKE' => array('postfix' => " ESCAPE '\\\\'"),
+      // Exists expects an already bracketed subquery as right hand part. Do
+      // not define additional brackets.
+      'EXISTS' => array(),
+      'NOT EXISTS' => array(),
       // These ones are here for performance reasons.
       '=' => array(),
       '<' => array(),