diff --git a/docs/Project.toml b/docs/Project.toml
index f8302d5..6f5a1d7 100644
--- a/docs/Project.toml
+++ b/docs/Project.toml
@@ -21,4 +21,5 @@ Documenter = "1.3"
 ForwardDiff = "1.3.1"
 Literate = "2.21.0"
 NLsolve = "4.5.1"
+Optim = "2.0.0"
 Zygote = "0.7.10"