diff --git a/test/Project.toml b/test/Project.toml
index d45be4ac..4966c2b4 100644
--- a/test/Project.toml
+++ b/test/Project.toml
@@ -3,11 +3,12 @@ Aqua = "4c88cf16-eb10-579e-8560-4a9242c79595"
 ChunkSplitters = "ae650224-84b6-46f8-82ea-d812ca08434e"
 DelimitedFiles = "8bb1440f-4735-579b-a4ab-409b98df4dab"
 Distributions = "31c24e10-a181-5473-b8eb-7969acd0382f"
+ForwardDiff = "f6369f11-7733-5829-9624-2563aa707210"
 GaussianRandomFields = "e4b2fa32-6e09-5554-b718-106ed5adafe9"
 HDF5 = "f67ccb44-e63f-5c2f-98bd-6dc0ccc4ba2f"
 LinearAlgebra = "37e2e46d-f89d-539d-b4ee-838fcccc9c8e"
 MPI = "da04e1cc-30fd-572f-bb4f-1f8673147195"
-OrdinaryDiffEq = "1dea7af3-3e70-54e6-95c3-0bf5283fa5ed"
+OrdinaryDiffEqTsit5 = "b1df2697-797e-41e3-8120-5422d3b24e4a"
 PDMats = "90014a1f-27ba-587c-ab20-58faa44d9150"
 Random = "9a3f8284-a2c9-5f02-9a11-845980a1fd5c"
 StableRNGs = "860ef19b-820b-49d6-a774-d7a799459cd3"
@@ -20,11 +21,12 @@ Aqua = "0.8"
 ChunkSplitters = "3.1"
 DelimitedFiles = "<0.0.1, 1"
 Distributions = "0.22, 0.23, 0.24, 0.25"
+ForwardDiff = "1.2"
 GaussianRandomFields = "2.2.1"
 HDF5 = "0.14, 0.15, 0.16, 0.17"
 LinearAlgebra = "<0.0.1, 1"
 MPI = "0.20.8"
-OrdinaryDiffEq = "6.40"
+OrdinaryDiffEqTsit5 = "1.5"
 PDMats = "0.11"
 Random = "<0.0.1, 1"
 StableRNGs = "1"
diff --git a/test/models/lorenz63.jl b/test/models/lorenz63.jl
index 1cf43561..d1b98ee7 100644
--- a/test/models/lorenz63.jl
+++ b/test/models/lorenz63.jl
@@ -5,7 +5,9 @@ using Distributions
 using HDF5
 using Random
 using PDMats
-using OrdinaryDiffEq
+# `ForwardDiff` is only needed to trigger loading a pkgextension.
+import ForwardDiff as _
+using OrdinaryDiffEqTsit5: OrdinaryDiffEqTsit5, Tsit5, ODEProblem, reinit!, step!
 using ParticleDA
 
 Base.@kwdef struct Lorenz63ModelParameters{S <: Real, T <: Real}
@@ -50,7 +52,7 @@ function init(
     parameters = get_params(Lorenz63ModelParameters{S, T}, parameters_dict)
     time_span = (0, parameters.time_step)
     integrators = [
-        OrdinaryDiffEq.init(
+        OrdinaryDiffEqTsit5.init(
             ODEProblem(update_time_derivative!, u, time_span, parameters), 
             Tsit5();
             save_everystep=false