diff --git a/src/wp-settings.php b/src/wp-settings.php
index f5a0929db87c1..04bf2fb1151ce 100644
--- a/src/wp-settings.php
+++ b/src/wp-settings.php
@@ -138,7 +138,7 @@
  *
  * @global string $table_prefix The database table prefix.
  */
-$GLOBALS['table_prefix'] = $table_prefix;
+$GLOBALS['table_prefix'] = isset( $GLOBALS['table_prefix'] ) ? $GLOBALS['table_prefix'] : $table_prefix;
 
 // Set the database table prefix and the format specifiers for database table columns.
 wp_set_wpdb_vars();