diff --git a/source/Control_Flow_Statements.rst b/source/Control_Flow_Statements.rst
index 53083a8fc6e84144fd01f1470f713a7090ffdde8..5a27b16d5035f6b4f83a963edc16f79b3a0c6b4d 100644
--- a/source/Control_Flow_Statements.rst
+++ b/source/Control_Flow_Statements.rst
@@ -79,7 +79,9 @@ implementation
    print my_max(l)
    58
    
-   
+
+.. _enzyme_exercise:
+
 Exercise
 --------