diff --git a/tutorial/exercise_01/instructions.md b/tutorial/exercise_01/instructions.md
index 0419f2f..d0c1cdb 100644
--- a/tutorial/exercise_01/instructions.md
+++ b/tutorial/exercise_01/instructions.md
@@ -35,8 +35,8 @@ More information on this topic can be found in our [user guide](http://vunit.git
 * Modify `run.py` to add a `tb_lib` library and add all source files in `test/` to that library
 
     ``` python
-    tb_lib = prj.add_library("tb_lib")
-    tb_lib.add_source_files(join(root, "test", "*.vhd"))
+    tb_lib = PRJ.add_library("tb_lib")
+    tb_lib.add_source_files(ROOT / "test" / "*.vhd")
     ```
 
 * Re-compile: