diff --git a/Project.toml b/Project.toml
index 063b6ae9b..0d5eb4840 100644
--- a/Project.toml
+++ b/Project.toml
@@ -30,7 +30,7 @@ DomainSets = "0.5, 0.6"
 IfElse = "0.1"
 Interpolations = "0.14"
 Latexify = "0.15, 0.16"
-ModelingToolkit = "8"
+ModelingToolkit = "8, 9"
 OrdinaryDiffEq = "6"
 PDEBase = "0.1.8"
 PrecompileTools = "1"