diff --git a/20.test/35.temporaryDsystem/30.c/textbook.en.md b/20.test/35.temporaryDsystem/30.c/textbook.en.md
index f52eeb8d2..22308cc80 100644
--- a/20.test/35.temporaryDsystem/30.c/textbook.en.md
+++ b/20.test/35.temporaryDsystem/30.c/textbook.en.md
@@ -1,10 +1,10 @@
 ---
 lessons:
-    - slug: test01-en
+    - slug: test01-Len
       order: 3
-    - slug: test02-en
+    - slug: test02-Len
       order: 3
-    - slug: test03-en
+    - slug: test03-Len
       order: 1
 ---