diff --git a/.github/workflows/Downgrade.yml b/.github/workflows/Downgrade.yml
index 2ea2136..8029f17 100644
--- a/.github/workflows/Downgrade.yml
+++ b/.github/workflows/Downgrade.yml
@@ -12,6 +12,7 @@ on:
       - 'docs/**'
 jobs:
   test:
+    if: false  # Disabled: waiting on dependency updates. See #100 for tracking.
     runs-on: ubuntu-latest
     strategy:
       matrix:
diff --git a/.github/workflows/Tests.yml b/.github/workflows/Tests.yml
index e95473f..0e79a04 100644
--- a/.github/workflows/Tests.yml
+++ b/.github/workflows/Tests.yml
@@ -18,11 +18,18 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
+        group:
+          - "Core"
+          - "nopre"
         version:
           - "1"
           - "lts"
           - "pre"
+        exclude:
+          - group: "nopre"
+            version: "pre"
     uses: "SciML/.github/.github/workflows/tests.yml@v1"
     with:
       julia-version: "${{ matrix.version }}"
+      group: "${{ matrix.group }}"
     secrets: "inherit"
diff --git a/Project.toml b/Project.toml
index e345b3b..b98cf80 100644
--- a/Project.toml
+++ b/Project.toml
@@ -1,7 +1,7 @@
 name = "SimpleDiffEq"
 uuid = "05bca326-078c-5bf0-a5bf-ce7c7982d7fd"
-repo = "https://github.com/SciML/SimpleDiffEq.jl.git"
 version = "1.12.0"
+repo = "https://github.com/SciML/SimpleDiffEq.jl.git"
 
 [deps]
 DiffEqBase = "2b5f629d-d688-5b77-993f-72d75c75574e"
@@ -28,8 +28,9 @@ julia = "1.6"
 ExplicitImports = "7d51a73a-1435-4ff3-83d9-f097790105c7"
 JLArrays = "27aeb0d3-9eb9-45fb-866b-73c2ecf80fcb"
 OrdinaryDiffEq = "1dea7af3-3e70-54e6-95c3-0bf5283fa5ed"
+Pkg = "44cfe95a-1eb2-52ea-b672-e2afdf69b78f"
 SafeTestsets = "1bc83da4-3b8d-516f-aca4-4fe02f6d838f"
 Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"
 
 [targets]
-test = ["ExplicitImports", "JLArrays", "OrdinaryDiffEq", "SafeTestsets", "Test"]
+test = ["ExplicitImports", "JLArrays", "OrdinaryDiffEq", "Pkg", "SafeTestsets", "Test"]
diff --git a/src/tsit5/atsit5.jl b/src/tsit5/atsit5.jl
index 8589812..9834647 100644
--- a/src/tsit5/atsit5.jl
+++ b/src/tsit5/atsit5.jl
@@ -692,25 +692,16 @@ end
 # Interpolation
 #######################################################################################
 # Interpolation function, both OOP and IIP
-@inline @muladd function (
-        integ::SAT5I{
-            IIP,
-            S,
-            T,
-        }
-    )(t::Real) where {
-        IIP,
-        S <:
-        AbstractArray{<:Number},
-        T,
-    }
+@inline @muladd function (integ::SAT5I{IIP, S, T})(
+        t::Real
+    ) where {IIP, S <: AbstractArray{<:Number}, T}
     tnext, tprev, dt = integ.t, integ.tprev, integ.dt
 
     θ = (t - tprev) / dt
     b1θ, b2θ, b3θ, b4θ, b5θ, b6θ, b7θ = bθs(integ.rs, θ)
 
     ks = integ.ks
-    if !IIP
+    if !isinplace(integ)
         u = @inbounds integ.uprev +
             dt * (
             b1θ * ks[1] + b2θ * ks[2] + b3θ * ks[3] + b4θ * ks[4] +
diff --git a/test/jet_tests.jl b/test/jet_tests.jl
new file mode 100644
index 0000000..c689ed8
--- /dev/null
+++ b/test/jet_tests.jl
@@ -0,0 +1,67 @@
+using SimpleDiffEq
+using JET
+using DiffEqBase
+using Test
+
+@testset "JET Static Analysis" begin
+    # Define test problems
+    f_scalar(u, p, t) = 1.01 * u
+    u0_scalar = 1.5
+    tspan = (0.0, 1.0)
+    prob_scalar = ODEProblem(f_scalar, u0_scalar, tspan)
+
+    function f_iip!(du, u, p, t)
+        du[1] = 1.01 * u[1]
+        du[2] = 2.0 * u[2]
+    end
+    u0_iip = [1.5, 2.0]
+    prob_iip = ODEProblem(f_iip!, u0_iip, tspan)
+
+    @testset "SimpleEuler type stability" begin
+        # OOP scalar
+        integ_oop = DiffEqBase.__init(prob_scalar, SimpleEuler(), dt = 0.1)
+        rep = JET.report_opt(DiffEqBase.step!, (typeof(integ_oop),))
+        @test length(JET.get_reports(rep)) == 0
+
+        # IIP array
+        integ_iip = DiffEqBase.__init(prob_iip, SimpleEuler(), dt = 0.1)
+        rep = JET.report_opt(DiffEqBase.step!, (typeof(integ_iip),))
+        @test length(JET.get_reports(rep)) == 0
+    end
+
+    @testset "SimpleRK4 type stability" begin
+        # OOP scalar
+        integ_oop = DiffEqBase.__init(prob_scalar, SimpleRK4(), dt = 0.1)
+        rep = JET.report_opt(DiffEqBase.step!, (typeof(integ_oop),))
+        @test length(JET.get_reports(rep)) == 0
+
+        # IIP array
+        integ_iip = DiffEqBase.__init(prob_iip, SimpleRK4(), dt = 0.1)
+        rep = JET.report_opt(DiffEqBase.step!, (typeof(integ_iip),))
+        @test length(JET.get_reports(rep)) == 0
+    end
+
+    @testset "SimpleTsit5 type stability" begin
+        # OOP scalar
+        integ_oop = DiffEqBase.__init(prob_scalar, SimpleTsit5(), dt = 0.1)
+        rep = JET.report_opt(DiffEqBase.step!, (typeof(integ_oop),))
+        @test length(JET.get_reports(rep)) == 0
+
+        # IIP array
+        integ_iip = DiffEqBase.__init(prob_iip, SimpleTsit5(), dt = 0.1)
+        rep = JET.report_opt(DiffEqBase.step!, (typeof(integ_iip),))
+        @test length(JET.get_reports(rep)) == 0
+    end
+
+    @testset "SimpleATsit5 type stability" begin
+        # OOP scalar
+        integ_oop = DiffEqBase.__init(prob_scalar, SimpleATsit5(), dt = 0.1)
+        rep = JET.report_opt(DiffEqBase.step!, (typeof(integ_oop),))
+        @test length(JET.get_reports(rep)) == 0
+
+        # IIP array
+        integ_iip = DiffEqBase.__init(prob_iip, SimpleATsit5(), dt = 0.1)
+        rep = JET.report_opt(DiffEqBase.step!, (typeof(integ_iip),))
+        @test length(JET.get_reports(rep)) == 0
+    end
+end
diff --git a/test/runtests.jl b/test/runtests.jl
index 863d5c7..ffd59d1 100644
--- a/test/runtests.jl
+++ b/test/runtests.jl
@@ -1,14 +1,24 @@
 using SimpleDiffEq, SafeTestsets, Test
 
+const GROUP = get(ENV, "GROUP", "Core")
+
 @time begin
-    @time @safetestset "ExplicitImports Tests" include("explicit_imports_tests.jl")
-    @time @safetestset "Discrete Tests" include("discrete_tests.jl")
-    @time @safetestset "SimpleEM Tests" include("simpleem_tests.jl")
-    @time @safetestset "SimpleTsit5 Tests" include("simpletsit5_tests.jl")
-    @time @safetestset "SimpleATsit5 Tests" include("simpleatsit5_tests.jl")
-    @time @safetestset "GPUSimpleATsit5 Tests" include("gpusimpleatsit5_tests.jl")
-    @time @safetestset "SimpleRK4 Tests" include("simplerk4_tests.jl")
-    @time @safetestset "SimpleEuler Tests" include("simpleeuler_tests.jl")
-    @time @safetestset "GPU Compatible ODE Tests" include("gpu_ode_regression.jl")
-    @time @safetestset "Interface Tests" include("interface_tests.jl")
+    if GROUP == "Core" || GROUP == "All"
+        @time @safetestset "ExplicitImports Tests" include("explicit_imports_tests.jl")
+        @time @safetestset "Discrete Tests" include("discrete_tests.jl")
+        @time @safetestset "SimpleEM Tests" include("simpleem_tests.jl")
+        @time @safetestset "SimpleTsit5 Tests" include("simpletsit5_tests.jl")
+        @time @safetestset "SimpleATsit5 Tests" include("simpleatsit5_tests.jl")
+        @time @safetestset "GPUSimpleATsit5 Tests" include("gpusimpleatsit5_tests.jl")
+        @time @safetestset "SimpleRK4 Tests" include("simplerk4_tests.jl")
+        @time @safetestset "SimpleEuler Tests" include("simpleeuler_tests.jl")
+        @time @safetestset "GPU Compatible ODE Tests" include("gpu_ode_regression.jl")
+        @time @safetestset "Interface Tests" include("interface_tests.jl")
+    end
+
+    if GROUP == "nopre"
+        import Pkg
+        Pkg.add("JET")
+        @time @safetestset "JET Static Analysis Tests" include("jet_tests.jl")
+    end
 end