diff --git a/tests/cases/Db/SQLite3/TestDriver.php b/tests/cases/Db/SQLite3/TestDriver.php
index 4c80cba..b3eb359 100644
--- a/tests/cases/Db/SQLite3/TestDriver.php
+++ b/tests/cases/Db/SQLite3/TestDriver.php
@@ -26,8 +26,10 @@ class TestDriver extends \JKingWeb\Arsse\TestCase\Db\BaseDriver {
     }
 
     public static function tearDownAfterClass(): void {
-        static::$interface->close();
-        static::$interface = null;
+        if (static::$interface) {
+            static::$interface->close();
+            static::$interface = null;
+        }
         parent::tearDownAfterClass();
         @unlink(static::$file);
         static::$file = null;
diff --git a/tests/cases/Db/SQLite3/TestResult.php b/tests/cases/Db/SQLite3/TestResult.php
index d7f8c09..5a8d0cd 100644
--- a/tests/cases/Db/SQLite3/TestResult.php
+++ b/tests/cases/Db/SQLite3/TestResult.php
@@ -16,8 +16,10 @@ class TestResult extends \JKingWeb\Arsse\TestCase\Db\BaseResult {
     protected static $createTest = "CREATE TABLE arsse_test(id integer primary key)";
 
     public static function tearDownAfterClass(): void {
-        static::$interface->close();
-        static::$interface = null;
+        if (static::$interface) {
+            static::$interface->close();
+            static::$interface = null;
+        }
         parent::tearDownAfterClass();
     }
 
diff --git a/tests/cases/Db/SQLite3/TestStatement.php b/tests/cases/Db/SQLite3/TestStatement.php
index 1af5be4..f7b970f 100644
--- a/tests/cases/Db/SQLite3/TestStatement.php
+++ b/tests/cases/Db/SQLite3/TestStatement.php
@@ -13,8 +13,10 @@ class TestStatement extends \JKingWeb\Arsse\TestCase\Db\BaseStatement {
     use \JKingWeb\Arsse\Test\DatabaseDrivers\SQLite3;
 
     public static function tearDownAfterClass(): void {
-        static::$interface->close();
-        static::$interface = null;
+        if (static::$interface) {
+            static::$interface->close();
+            static::$interface = null;
+        }
         parent::tearDownAfterClass();
     }
 
diff --git a/tests/cases/Db/SQLite3/TestUpdate.php b/tests/cases/Db/SQLite3/TestUpdate.php
index 94842e2..409f109 100644
--- a/tests/cases/Db/SQLite3/TestUpdate.php
+++ b/tests/cases/Db/SQLite3/TestUpdate.php
@@ -16,8 +16,10 @@ class TestUpdate extends \JKingWeb\Arsse\TestCase\Db\BaseUpdate {
     protected static $minimal2 = "pragma user_version=2";
 
     public static function tearDownAfterClass(): void {
-        static::$interface->close();
-        static::$interface = null;
+        if (static::$interface) {
+            static::$interface->close();
+            static::$interface = null;
+        }
         parent::tearDownAfterClass();
     }
 }
diff --git a/tests/lib/DatabaseDrivers/MySQL.php b/tests/lib/DatabaseDrivers/MySQL.php
index f1571a2..01501f1 100644
--- a/tests/lib/DatabaseDrivers/MySQL.php
+++ b/tests/lib/DatabaseDrivers/MySQL.php
@@ -18,9 +18,12 @@ trait MySQL {
     protected static $stringOutput = true;
 
     public static function dbInterface() {
+        if (!class_exists("mysqli")) {
+            return null;
+        }
         $d = @new \mysqli(Arsse::$conf->dbMySQLHost, Arsse::$conf->dbMySQLUser, Arsse::$conf->dbMySQLPass, Arsse::$conf->dbMySQLDb, Arsse::$conf->dbMySQLPort);
         if ($d->connect_errno) {
-            return;
+            return null;
         }
         $d->set_charset("utf8mb4");
         foreach (\JKingWeb\Arsse\Db\MySQL\PDODriver::makeSetupQueries() as $q) {
diff --git a/tests/lib/DatabaseDrivers/PostgreSQL.php b/tests/lib/DatabaseDrivers/PostgreSQL.php
index fb0038c..edc7549 100644
--- a/tests/lib/DatabaseDrivers/PostgreSQL.php
+++ b/tests/lib/DatabaseDrivers/PostgreSQL.php
@@ -19,7 +19,7 @@ trait PostgreSQL {
 
     public static function dbInterface() {
         $connString = \JKingWeb\Arsse\Db\PostgreSQL\Driver::makeConnectionString(false, Arsse::$conf->dbPostgreSQLUser, Arsse::$conf->dbPostgreSQLPass, Arsse::$conf->dbPostgreSQLDb, Arsse::$conf->dbPostgreSQLHost, Arsse::$conf->dbPostgreSQLPort, "");
-        if ($d = @pg_connect($connString, \PGSQL_CONNECT_FORCE_NEW)) {
+        if (function_exists("pg_connect") && $d = @pg_connect($connString, \PGSQL_CONNECT_FORCE_NEW)) {
             foreach (\JKingWeb\Arsse\Db\PostgreSQL\Driver::makeSetupQueries(Arsse::$conf->dbPostgreSQLSchema) as $q) {
                 pg_query($d, $q);
             }