diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index f9a9965..6cc6a2b 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -125,6 +125,8 @@ jobs:
                       db: "mysql:5.7"
                     - php: '8.2'
                       db: "mysql:5.7"
+                    - php: '8.3'
+                      db: "mysql:5.7"
 
         name: PHP ${{ matrix.php }} - ${{ matrix.db_alias != '' && matrix.db_alias || matrix.db }}
 
@@ -266,6 +268,8 @@ jobs:
                       db: "postgres:14"
                     - php: '8.2'
                       db: "postgres:14"
+                    - php: '8.3'
+                      db: "postgres:14"
 
         name: PHP ${{ matrix.php }} - ${{ matrix.db }}
 
diff --git a/composer.json b/composer.json
index 5ed16ee..a88adc8 100644
--- a/composer.json
+++ b/composer.json
@@ -32,7 +32,8 @@
 		"version-check": {
 			"host": "www.phpbb.com",
 			"directory": "/customise/db/extension/topicprefixes",
-			"filename": "version_check"
+			"filename": "version_check",
+			"ssl": true
 		}
 	}
 }
diff --git a/controller/admin_controller.php b/controller/admin_controller.php
index 2fc85f6..c02b29e 100644
--- a/controller/admin_controller.php
+++ b/controller/admin_controller.php
@@ -155,7 +155,11 @@ public function add_prefix()
 
 			$tag = $this->request->variable('prefix_tag', '', true);
 			$prefix = $this->manager->add_prefix($tag, $this->forum_id);
-			$this->log($prefix['prefix_tag'], 'ACP_LOG_PREFIX_ADDED');
+
+			if ($prefix)
+			{
+				$this->log($prefix['prefix_tag'], 'ACP_LOG_PREFIX_ADDED');
+			}
 		}
 	}
 
diff --git a/tests/controller/add_prefix_test.php b/tests/controller/add_prefix_test.php
index 09978bd..d239e56 100644
--- a/tests/controller/add_prefix_test.php
+++ b/tests/controller/add_prefix_test.php
@@ -25,21 +25,23 @@ class add_prefix_test extends admin_controller_base
 	 */
 	public function data_add_prefix()
 	{
-		return array(
-			array(true, true),
-			array(true, false),
-			array(false, false),
-		);
+		return [
+			['', true, true],
+			['topic_prefix1', true, true],
+			['topic_prefix2', true, false],
+			['topic_prefix3', false, false],
+		];
 	}
 
 	/**
 	 * Test add_prefix()
 	 *
 	 * @dataProvider data_add_prefix
+	 * @param $prefix
 	 * @param $submit
 	 * @param $valid_form
 	 */
-	public function test_add_prefix($submit, $valid_form)
+	public function test_add_prefix($prefix, $submit, $valid_form)
 	{
 		if ($submit)
 		{
@@ -52,20 +54,26 @@ public function test_add_prefix($submit, $valid_form)
 			if (!$valid_form)
 			{
 				// Throws E_WARNING in PHP 8.0+ and E_USER_WARNING in earlier versions
-				$exceptionName = version_compare(PHP_VERSION, '8.0', '<') ? \PHPUnit\Framework\Error\Error::class : \PHPUnit\Framework\Error\Warning::class;
-				$errno = version_compare(PHP_VERSION, '8.0', '<') ? E_USER_WARNING : E_WARNING;
+				$exceptionName = PHP_VERSION_ID < 80000 ? \PHPUnit\Framework\Error\Error::class : \PHPUnit\Framework\Error\Warning::class;
+				$errno = PHP_VERSION_ID < 80000 ? E_USER_WARNING : E_WARNING;
 				$this->expectException($exceptionName);
 				$this->expectExceptionCode($errno);
 			}
 			else
 			{
+				$valid_prefix = $prefix !== '';
+				$this->request->expects(static::once())
+					->method('variable')
+					->willReturnMap([
+						['prefix_tag', '', true, \phpbb\request\request_interface::REQUEST, $prefix],
+					]);
 				$this->manager->expects(static::once())
 					->method('add_prefix')
-					->willReturn(['prefix_tag' => 'topic_prefix']);
-				$this->log->expects(static::once())
+					->willReturn($valid_prefix ? ['prefix_tag' => $prefix] : false);
+				$this->log->expects($valid_prefix ? static::once() : static::never())
 					->method('add')
-					->with('admin', static::anything(), static::anything(), 'ACP_LOG_PREFIX_ADDED', static::anything(), ['topic_prefix', 'Test Forum']);
-				$this->db->expects(static::once())
+					->with('admin', static::anything(), static::anything(), 'ACP_LOG_PREFIX_ADDED', static::anything(), [$prefix, 'Test Forum']);
+				$this->db->expects($valid_prefix ? static::once() : static::never())
 					->method('sql_fetchrow')
 					->willReturn(['forum_name' => 'Test Forum']);
 			}