diff --git a/tests/template/template_test.php b/tests/template/template_test.php
index 1649604492..c28c7a70bc 100644
--- a/tests/template/template_test.php
+++ b/tests/template/template_test.php
@@ -237,7 +237,7 @@ class phpbb_template_template_test extends phpbb_template_template_test_case
 				array('VARIABLE' => 'variable.html'),
 				array(),
 				array(),
-				'variable.html',
+				'variable.htmlvariable.html',
 			),
 			array(
 				'include_loop_define.html',
diff --git a/tests/template/templates/include_define_variable.html b/tests/template/templates/include_define_variable.html
index aff9b574c2..fceeebf5df 100644
--- a/tests/template/templates/include_define_variable.html
+++ b/tests/template/templates/include_define_variable.html
@@ -1,2 +1,4 @@
 <!-- DEFINE $DEF = '{VARIABLE}' -->
 <!-- INCLUDE {$DEF} -->
+<!-- DEFINE $DEF_WITH_UNDERSCORES = '{VARIABLE}' -->
+<!-- INCLUDE {$DEF_WITH_UNDERSCORES} -->