diff --git a/book/intro.md b/book/intro.md
index c70a559..c51c487 100644
--- a/book/intro.md
+++ b/book/intro.md
@@ -15,7 +15,7 @@ kernelspec:
 
 This is a parent theorem. This text is inside the parent theorem.
 
-:::{prf:axiom-start} A child theorem
+:::{prf:axiom-start} A child axiom
 :label: child-axiom-label
 
 This is a child axiom. This text is inside the child directive.
diff --git a/requirements.txt b/requirements.txt
index 3b6ef5b..1c93c95 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -11,3 +11,5 @@ sphinx-apa-references
 myst_nb
 numpy
 matplotlib
+
+sphinx-tudelft-theme == 1.2.1
\ No newline at end of file