diff --git a/core/lib/Drupal/Core/Database/Query/Condition.php b/core/lib/Drupal/Core/Database/Query/Condition.php
index ec541c1..00e9015 100644
--- a/core/lib/Drupal/Core/Database/Query/Condition.php
+++ b/core/lib/Drupal/Core/Database/Query/Condition.php
@@ -165,7 +165,7 @@ public function compile(Connection $connection, PlaceholderInterface $queryPlace
       foreach ($conditions as $condition) {
         // Process field.
         if ($condition['field'] instanceof ConditionInterface) {
-          // Left hand part is a structured condition or a subquery: compile,
+          // Left hand part is a structured condition or a subquery. Compile,
           // put brackets around it (if it is a query), and collect any
           // arguments.
           $condition['field']->compile($connection, $queryPlaceholder);
@@ -174,25 +174,29 @@ public function compile(Connection $connection, PlaceholderInterface $queryPlace
             $field_fragment = '(' . $field_fragment . ')';
           }
           $arguments += $condition['field']->arguments();
+          // If the operator and value were not passed in to the
+          // @see ConditionInterface::condition() method (and thus have the
+          // default value as defined over there) it is assumed to be a valid
+          // condition on its own: ignore the operator and value parts.
+          $ignore_operator = $condition['operator'] === '=' && $condition['value'] === NULL;
         }
         else if (!isset($condition['operator'])) {
           // Left hand part is a literal string added with the
           // @see ConditionInterface::where() method. Put brackets around
           // the snippet and collect the arguments from the value part.
+          // Also ignore the operator and value parts.
           $field_fragment = '(' . $condition['field'] . ')';
           $arguments += $condition['value'];
+          $ignore_operator = TRUE;
         }
         else {
-          // Left hand part is a normal field: add it as is.
+          // Left hand part is a normal field. Add it as is.
           $field_fragment = $condition['field'];
+          $ignore_operator = FALSE;
         }
 
         // Process operator.
-        if ($condition['value'] === NULL && $condition['field'] instanceof ConditionInterface && $condition['operator'] === '=') {
-          // If the operator and value were not passed in (and thus have the
-          // default value as defined by the condition() method) and the field
-          // is a Condition, it is assumed to be a valid condition on its own:
-          // ignore the operator and value parts.
+        if ($ignore_operator) {
           $operator = array('operator' => '', 'use_value' => FALSE);
         }
         else {
@@ -255,14 +259,14 @@ public function compile(Connection $connection, PlaceholderInterface $queryPlace
           $value_fragment = array();
           foreach ($condition['value'] as $value) {
             if ($value instanceof ConditionInterface) {
-              // Right hand part is a subquery: compile, assure that brackets
+              // Right hand part is a subquery. Compile, assure that brackets
               // are put around it and collect any arguments.
               $value->compile($connection, $queryPlaceholder);
               $value_fragment[] = '(' . (string) $value . ')';
               $arguments += $value->arguments();
             }
             else {
-              // Right hand part is a normal value: replace the value with a
+              // Right hand part is a normal value. Replace the value with a
               // placeholder and add the value as an argument.
               $placeholder = ':db_condition_placeholder_' . $queryPlaceholder->nextPlaceholder();
               $value_fragment[] = $placeholder;