diff --git a/core/lib/Drupal/Core/Database/Php8StatementTrait.php b/core/lib/Drupal/Core/Database/Php8StatementTrait.php
index 7224e545b5..b1b5dbf3c1 100644
--- a/core/lib/Drupal/Core/Database/Php8StatementTrait.php
+++ b/core/lib/Drupal/Core/Database/Php8StatementTrait.php
@@ -14,8 +14,10 @@ trait Php8StatementTrait {
    * constants used.
    *
    * @param int $mode
-   *   One of the PDO::FETCH_* constants.
-   *   Default to what was specified by setFetchMode().
+   *   One of the PDO::FETCH_* constants. Defaults to what was specified by
+   *   setFetchMode(). Note the default value on the implementation is different
+   *   from the default value on \PDO::fetch() for PHP 8 in order to allow
+   *   \Drupal\Core\Database\StatementPrefetch to behave the same on PHP 7 & 8.
    * @param int $cursor_orientation
    *   Not implemented in all database drivers, don't use.
    * @param int $cursor_offset
@@ -24,7 +26,7 @@ trait Php8StatementTrait {
    * @return
    *   A result, formatted according to $mode.
    */
-  public function fetch(int $mode = \PDO::FETCH_BOTH, int $cursor_orientation = \PDO::FETCH_ORI_NEXT, int $cursor_offset = 0) {
+  public function fetch(int $mode = 0, int $cursor_orientation = \PDO::FETCH_ORI_NEXT, int $cursor_offset = 0) {
     return $this->doFetch($mode, $cursor_orientation, $cursor_offset);
   }
 
diff --git a/core/lib/Drupal/Core/Database/StatementPrefetch.php b/core/lib/Drupal/Core/Database/StatementPrefetch.php
index 3c46426772..845f366585 100644
--- a/core/lib/Drupal/Core/Database/StatementPrefetch.php
+++ b/core/lib/Drupal/Core/Database/StatementPrefetch.php
@@ -396,7 +396,7 @@ public function rowCount() {
   public function doFetch($mode) {
     if (isset($this->currentRow)) {
       // Set the fetch parameter.
-      $this->fetchStyle = isset($mode) ? $mode : $this->defaultFetchStyle;
+      $this->fetchStyle = !empty($mode) ? $mode : $this->defaultFetchStyle;
       $this->fetchOptions = $this->defaultFetchOptions;
 
       // Grab the row in the format specified above.