diff --git a/src/c/CMakeLists.txt b/src/c/CMakeLists.txt
index 9f88703..1926336 100644
--- a/src/c/CMakeLists.txt
+++ b/src/c/CMakeLists.txt
@@ -1,12 +1,12 @@
 include(AddLesson)
 
-add_lesson(lesson1 SOURCES lesson1.c)
-add_lesson(lesson2 SOURCES lesson2.c SHADERS lesson2.metallib)
-add_lesson(lesson3 SOURCES lesson3.c SHADERS lesson3.metallib)
-add_lesson(lesson4 SOURCES lesson4.c SHADERS lesson3.metallib)
-add_lesson(lesson5 SOURCES lesson5.c SHADERS lesson3.metallib)
-add_lesson(lesson6 SOURCES lesson6.c SHADERS lesson6.metallib DATA NeHe.bmp)
-add_lesson(lesson7 SOURCES lesson7.c SHADERS lesson6.metallib lesson7.metallib DATA Crate.bmp)
-add_lesson(lesson8 SOURCES lesson8.c SHADERS lesson6.metallib lesson7.metallib DATA Glass.bmp)
-add_lesson(lesson9 SOURCES lesson9.c SHADERS lesson6.metallib lesson9.metallib DATA Star.bmp)
+add_lesson(lesson01 SOURCES lesson1.c)
+add_lesson(lesson02 SOURCES lesson2.c SHADERS lesson2.metallib)
+add_lesson(lesson03 SOURCES lesson3.c SHADERS lesson3.metallib)
+add_lesson(lesson04 SOURCES lesson4.c SHADERS lesson3.metallib)
+add_lesson(lesson05 SOURCES lesson5.c SHADERS lesson3.metallib)
+add_lesson(lesson06 SOURCES lesson6.c SHADERS lesson6.metallib DATA NeHe.bmp)
+add_lesson(lesson07 SOURCES lesson7.c SHADERS lesson6.metallib lesson7.metallib DATA Crate.bmp)
+add_lesson(lesson08 SOURCES lesson8.c SHADERS lesson6.metallib lesson7.metallib DATA Glass.bmp)
+add_lesson(lesson09 SOURCES lesson9.c SHADERS lesson6.metallib lesson9.metallib DATA Star.bmp)
 add_lesson(lesson10 SOURCES lesson10.c SHADERS lesson6.metallib DATA Mud.bmp World.txt)