diff --git a/Project.toml b/Project.toml
index c79438839..943cf6737 100644
--- a/Project.toml
+++ b/Project.toml
@@ -18,6 +18,7 @@ Symbolics = "0c5d862f-8b57-4792-8d23-62f2024744c7"
 Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"
 
 [compat]
+DiffEqOperators = "4"
 DomainSets = "0.5"
 ModelingToolkit = "8"
 NonlinearSolve = "0.3"