diff --git a/docs/Project.toml b/docs/Project.toml
index cc3e747..8a67af6 100644
--- a/docs/Project.toml
+++ b/docs/Project.toml
@@ -5,3 +5,4 @@ DocumenterTools = "35a29f4d-8980-5a13-9543-d66fff28ecb8"
 
 [compat]
 Documenter = "1"
+DocumenterTools = "0.1.21"