diff --git a/lib/ControlSystemsBase/Project.toml b/lib/ControlSystemsBase/Project.toml
index e525a91ac..024ef3b37 100644
--- a/lib/ControlSystemsBase/Project.toml
+++ b/lib/ControlSystemsBase/Project.toml
@@ -1,8 +1,8 @@
 name = "ControlSystemsBase"
 uuid = "aaaaaaaa-a6ca-5380-bf3e-84a91bcd477e"
+version = "1.20.1"
 authors = ["Dept. Automatic Control, Lund University"]
 repo = "https://github.com/JuliaControl/ControlSystems.jl.git"
-version = "1.20.1"
 
 [deps]
 ForwardDiff = "f6369f11-7733-5829-9624-2563aa707210"
@@ -36,7 +36,7 @@ ComponentArrays = "0.15"
 DSP = "0.6.1, 0.7, 0.8"
 ForwardDiff = "0.10, 1.0"
 Hungarian = "0.7.0"
-ImplicitDifferentiation = "0.7.2"
+ImplicitDifferentiation = "0.7.2, 0.9"
 LinearAlgebra = "<0.0.1, 1"
 MacroTools = "0.5"
 Makie = "0.24"