diff --git a/conf/default.conf.php b/conf/default.conf.php
index 0089844e88..4da799d1a4 100644
--- a/conf/default.conf.php
+++ b/conf/default.conf.php
@@ -174,7 +174,9 @@ return array(
   // Phabricator supports PHP extensions MySQL and MySQLi. It is possible to
   // implement also other access mechanism (e.g. PDO_MySQL). The class must
   // extend AphrontMySQLDatabaseConnectionBase.
-  'mysql.implementation' => 'AphrontMySQLDatabaseConnection',
+  'mysql.implementation' => (extension_loaded('mysqli')
+    ? 'AphrontMySQLiDatabaseConnection'
+    : 'AphrontMySQLDatabaseConnection'),
 
 
 // -- Notifications --------------------------------------------------------- //
diff --git a/src/applications/config/option/PhabricatorMySQLConfigOptions.php b/src/applications/config/option/PhabricatorMySQLConfigOptions.php
index 05741f4ba6..5165fe0a75 100644
--- a/src/applications/config/option/PhabricatorMySQLConfigOptions.php
+++ b/src/applications/config/option/PhabricatorMySQLConfigOptions.php
@@ -43,7 +43,9 @@ final class PhabricatorMySQLConfigOptions
       $this->newOption(
         'mysql.implementation',
         'class',
-        'AphrontMySQLDatabaseConnection')
+        (extension_loaded('mysqli')
+          ? 'AphrontMySQLiDatabaseConnection'
+          : 'AphrontMySQLDatabaseConnection'))
         ->setLocked(true)
         ->setBaseClass('AphrontMySQLDatabaseConnectionBase')
         ->setSummary(