diff --git a/tests/cases/Db/BaseDriver.php b/tests/cases/Db/BaseDriver.php
index fd8cb5a..5f30991 100644
--- a/tests/cases/Db/BaseDriver.php
+++ b/tests/cases/Db/BaseDriver.php
@@ -49,14 +49,14 @@ abstract class BaseDriver extends \JKingWeb\Arsse\Test\AbstractTest {
     public function tearDown() {
         // deconstruct the driver
         unset($this->drv);
-        if (static::$interface) {
-            // completely clear the database
-            (static::$dbInfo->razeFunction)(static::$interface);
-        }
         self::clearData();
     }
 
     public static function tearDownAfterClass() {
+        if (static::$interface) {
+            // completely clear the database
+            (static::$dbInfo->razeFunction)(static::$interface);
+        }
         static::$interface = null;
         static::$dbInfo = null;
         self::clearData();
diff --git a/tests/cases/Db/BaseResult.php b/tests/cases/Db/BaseResult.php
index a2159e4..bb1725b 100644
--- a/tests/cases/Db/BaseResult.php
+++ b/tests/cases/Db/BaseResult.php
@@ -38,15 +38,15 @@ abstract class BaseResult extends \JKingWeb\Arsse\Test\AbstractTest {
     }
 
     public function tearDown() {
-        if (static::$interface) {
-            // completely clear the database
-            (static::$dbInfo->razeFunction)(static::$interface);
-        }
         self::clearData();
     }
 
     public static function tearDownAfterClass() {
-        static::$implementation = null;
+        if (static::$interface) {
+            // completely clear the database
+            (static::$dbInfo->razeFunction)(static::$interface);
+        }
+        static::$interface = null;
         static::$dbInfo = null;
         self::clearData();
     }
diff --git a/tests/cases/Db/BaseStatement.php b/tests/cases/Db/BaseStatement.php
index 92750e9..c3c3704 100644
--- a/tests/cases/Db/BaseStatement.php
+++ b/tests/cases/Db/BaseStatement.php
@@ -39,15 +39,15 @@ abstract class BaseStatement extends \JKingWeb\Arsse\Test\AbstractTest {
     }
 
     public function tearDown() {
-        if (static::$interface) {
-            // completely clear the database
-            (static::$dbInfo->razeFunction)(static::$interface);
-        }
         self::clearData();
     }
 
     public static function tearDownAfterClass() {
-        static::$implementation = null;
+        if (static::$interface) {
+            // completely clear the database
+            (static::$dbInfo->razeFunction)(static::$interface);
+        }
+        static::$interface = null;
         static::$dbInfo = null;
         self::clearData();
     }
diff --git a/tests/cases/Db/BaseUpdate.php b/tests/cases/Db/BaseUpdate.php
index b4de0ea..28cde46 100644
--- a/tests/cases/Db/BaseUpdate.php
+++ b/tests/cases/Db/BaseUpdate.php
@@ -48,16 +48,16 @@ class BaseUpdate extends \JKingWeb\Arsse\Test\AbstractTest {
     public function tearDown() {
         // deconstruct the driver
         unset($this->drv);
-        if (static::$interface) {
-            // completely clear the database
-            (static::$dbInfo->razeFunction)(static::$interface);
-        }
         unset($this->path, $this->base, $this->vfs);
         self::clearData();
     }
 
     public static function tearDownAfterClass() {
-        static::$implementation = null;
+        if (static::$interface) {
+            // completely clear the database
+            (static::$dbInfo->razeFunction)(static::$interface);
+        }
+        static::$interface = null;
         static::$dbInfo = null;
         self::clearData();
     }
diff --git a/tests/cases/Db/SQLite3/TestDriver.php b/tests/cases/Db/SQLite3/TestDriver.php
index 9b2348a..334a784 100644
--- a/tests/cases/Db/SQLite3/TestDriver.php
+++ b/tests/cases/Db/SQLite3/TestDriver.php
@@ -25,9 +25,8 @@ class TestDriver extends \JKingWeb\Arsse\TestCase\Db\BaseDriver {
     }
 
     public static function tearDownAfterClass() {
-        if (static::$interface) {
-            static::$interface->close();
-        }
+        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 1b34a1d..4f6780a 100644
--- a/tests/cases/Db/SQLite3/TestResult.php
+++ b/tests/cases/Db/SQLite3/TestResult.php
@@ -17,9 +17,8 @@ class TestResult extends \JKingWeb\Arsse\TestCase\Db\BaseResult {
     protected static $createTest = "CREATE TABLE arsse_test(id integer primary key)";
 
     public static function tearDownAfterClass() {
-        if (static::$interface) {
-            static::$interface->close();
-        }
+        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 1684e83..7471b41 100644
--- a/tests/cases/Db/SQLite3/TestStatement.php
+++ b/tests/cases/Db/SQLite3/TestStatement.php
@@ -14,6 +14,7 @@ class TestStatement extends \JKingWeb\Arsse\TestCase\Db\BaseStatement {
 
     public static function tearDownAfterClass() {
         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 ecea58b..5331085 100644
--- a/tests/cases/Db/SQLite3/TestUpdate.php
+++ b/tests/cases/Db/SQLite3/TestUpdate.php
@@ -13,4 +13,10 @@ class TestUpdate extends \JKingWeb\Arsse\TestCase\Db\BaseUpdate {
     protected static $implementation = "SQLite 3";
     protected static $minimal1 = "create table arsse_meta(key text primary key not null, value text); pragma user_version=1";
     protected static $minimal2 = "pragma user_version=2";
+
+    public static function tearDownAfterClass() {
+        static::$interface->close();
+        static::$interface = null;
+        parent::tearDownAfterClass();
+    }
 }