diff --git a/20.test/36.temporaryDDsystem/10.a/30.en/textbook.en.md b/20.test/36.temporaryDDsystem/10.a/30.en/textbook.en.md
index 4a842c315..742469aab 100644
--- a/20.test/36.temporaryDDsystem/10.a/30.en/textbook.en.md
+++ b/20.test/36.temporaryDDsystem/10.a/30.en/textbook.en.md
@@ -1,10 +1,10 @@
 ---
 lessons:
-    - slug: test01
+    - slug: test01-en
       order: 1
-    - slug: test02
+    - slug: test02-en
       order: 2
-    - slug: test03
+    - slug: test03-en
       order: 2
 ---