diff --git a/tests/dbal/db_tools_test.php b/tests/dbal/db_tools_test.php
index 516fb9e739..9bed0648cd 100644
--- a/tests/dbal/db_tools_test.php
+++ b/tests/dbal/db_tools_test.php
@@ -106,7 +106,7 @@ class phpbb_dbal_db_tools_test extends phpbb_database_test_case
 			'c_bool' => 0,
 			'c_vchar' => '',
 			'c_vchar_size' => '',
-			'c_char_size' => '',
+			'c_char_size' => 'abcd',
 			'c_xstext' => '',
 			'c_stext' => '',
 			'c_text' => '',