diff --git a/docs/Project.toml b/docs/Project.toml
index 44827d163b..377e4be0c3 100644
--- a/docs/Project.toml
+++ b/docs/Project.toml
@@ -44,6 +44,7 @@ Documenter = "1"
 DynamicQuantities = "^0.11.2, 0.12, 1"
 FMI = "0.14"
 FMIZoo = "1"
+Ipopt = "1"
 JumpProcesses = "9"
 ModelingToolkit = "10"
 ModelingToolkitStandardLibrary = "2.19"