diff --git a/chapter_01_domain_model.asciidoc b/chapter_01_domain_model.asciidoc
index 1df7a12f..a8be4c82 100644
--- a/chapter_01_domain_model.asciidoc
+++ b/chapter_01_domain_model.asciidoc
@@ -655,7 +655,7 @@ object, though. In fact, it's common to support operations on values; for
 example, mathematical operators:
 
 
-[[value_object_maths]]
+[[value_object_maths_tests]]
 .Testing Math with value objects
 ====
 [source,python]