diff --git a/docs/Project.toml b/docs/Project.toml
index 9234df1..1236958 100644
--- a/docs/Project.toml
+++ b/docs/Project.toml
@@ -12,7 +12,7 @@ MarkdownAST = "d0879d2d-cac2-40c8-9cee-1863dc0c7391"
 
 [compat]
 ADTypes = "1"
-CTBase = "0.25"
+CTBase = "0.25, 0.18"
 DifferentiationInterface = "0.7"
 Documenter = "1"
 DocumenterInterLinks = "1"