diff --git a/docs/Project.toml b/docs/Project.toml
index 30d7aef81..d18d150d7 100644
--- a/docs/Project.toml
+++ b/docs/Project.toml
@@ -41,7 +41,7 @@ CTBase = "0.30"
 CTDirect = "1"
 CTFlows = "0.18"
 CTLie = "0.2"
-CTModels = "0.19"
+CTModels = "0.19, 0.21"
 CTParser = "0.9"
 CTSolvers = "0.5"
 CUDA = "6"