diff --git a/docs/Project.toml b/docs/Project.toml
index ef28ea6a..48fcfd0d 100644
--- a/docs/Project.toml
+++ b/docs/Project.toml
@@ -7,7 +7,7 @@ MarkdownAST = "d0879d2d-cac2-40c8-9cee-1863dc0c7391"
 Plots = "91a5bcdd-55d7-5caf-9e0b-520d859cae80"
 
 [compat]
-CTBase = "0.26"
+CTBase = "0.26, 0.18"
 Documenter = "1"
 JLD2 = "0.6"
 JSON3 = "1"