diff --git a/tests/include-skipif.php b/tests/include-skipif.inc
similarity index 100%
rename from tests/include-skipif.php
rename to tests/include-skipif.inc
diff --git a/tests/sub-a.php b/tests/sub-a.inc
similarity index 100%
rename from tests/sub-a.php
rename to tests/sub-a.inc
diff --git a/tests/sub-b.php b/tests/sub-b.inc
similarity index 100%
rename from tests/sub-b.php
rename to tests/sub-b.inc
diff --git a/tests/xcache_include_absolute.phpt b/tests/xcache_include_absolute.phpt
index 76598f4..f4c7e56 100644
--- a/tests/xcache_include_absolute.phpt
+++ b/tests/xcache_include_absolute.phpt
@@ -2,15 +2,15 @@
 include absolute path
 --SKIPIF--
 <?php
-require("include-skipif.php");
+require("include-skipif.inc");
 ?>
 --FILE--
 <?php
-include __DIR__ . "/sub-a.php";
-include __DIR__ . "/sub-b.php";
+include __DIR__ . "/sub-a.inc";
+include __DIR__ . "/sub-b.inc";
 ?>
 --EXPECTF--
 %stests
-%stests%ssub-a.php
+%stests%ssub-a.inc
 %stests
-%stests%ssub-b.php
+%stests%ssub-b.inc
diff --git a/tests/xcache_include_relative_cwd.phpt b/tests/xcache_include_relative_cwd.phpt
index 580a459..13f9d33 100644
--- a/tests/xcache_include_relative_cwd.phpt
+++ b/tests/xcache_include_relative_cwd.phpt
@@ -2,16 +2,16 @@
 include relative to current working dir
 --SKIPIF--
 <?php
-require("include-skipif.php");
+require("include-skipif.inc");
 ?>
 --FILE--
 <?php
 chdir(__DIR__);
-include "./sub-a.php";
-include "./sub-b.php";
+include "./sub-a.inc";
+include "./sub-b.inc";
 ?>
 --EXPECTF--
 %stests
-%stests%ssub-a.php
+%stests%ssub-a.inc
 %stests
-%stests%ssub-b.php
+%stests%ssub-b.inc
diff --git a/tests/xcache_include_relative_file.phpt b/tests/xcache_include_relative_file.phpt
index c291b82..c86ada1 100644
--- a/tests/xcache_include_relative_file.phpt
+++ b/tests/xcache_include_relative_file.phpt
@@ -2,15 +2,15 @@
 include relative to current file
 --SKIPIF--
 <?php
-require("include-skipif.php");
+require("include-skipif.inc");
 ?>
 --FILE--
 <?php
-include "sub-a.php";
-include "sub-b.php";
+include "sub-a.inc";
+include "sub-b.inc";
 ?>
 --EXPECTF--
 %stests
-%stests%ssub-a.php
+%stests%ssub-a.inc
 %stests
-%stests%ssub-b.php
+%stests%ssub-b.inc