diff --git a/Project.toml b/Project.toml
index 623193e..d1cdc2c 100644
--- a/Project.toml
+++ b/Project.toml
@@ -13,13 +13,15 @@ ForwardDiff = "f6369f11-7733-5829-9624-2563aa707210"
 ThickNumbersForwardDiffExt = "ForwardDiff"
 
 [compat]
+DifferentiationInterface = "0.6"
 ForwardDiff = "0.10, 1"
 LinearAlgebra = "1"
 julia = "1.9"
 
 [extras]
+DifferentiationInterface = "a0c0ee7d-e4b9-4e03-894e-1c5f64a51d63"
 ForwardDiff = "f6369f11-7733-5829-9624-2563aa707210"
 Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"
 
 [targets]
-test = ["ForwardDiff", "Test"]
+test = ["DifferentiationInterface", "ForwardDiff", "Test"]
diff --git a/ThickNumbersInterfaceTests/test/testpackages/IntervalArith/src/IntervalArith.jl b/ThickNumbersInterfaceTests/test/testpackages/IntervalArith/src/IntervalArith.jl
index c7cd510..d32cc9e 100644
--- a/ThickNumbersInterfaceTests/test/testpackages/IntervalArith/src/IntervalArith.jl
+++ b/ThickNumbersInterfaceTests/test/testpackages/IntervalArith/src/IntervalArith.jl
@@ -44,4 +44,6 @@ end
 Base.abs2(x::Interval) = Interval(mig(x)^2, mag(x)^2)
 Base.sqrt(x::Interval) = Interval(sqrt(loval(x)), sqrt(hival(x)))
 
+Base.conj(x::Interval{T}) where T = Interval{T}(conj(x.lo), conj(x.hi))   # needed for Enzyme
+
 end # module IntervalArith
diff --git a/test/extensions/di.jl b/test/extensions/di.jl
new file mode 100644
index 0000000..f059037
--- /dev/null
+++ b/test/extensions/di.jl
@@ -0,0 +1,39 @@
+using ThickNumbers
+using DifferentiationInterface
+using ForwardDiff
+
+using Test
+
+include(joinpath(dirname(@__DIR__), "setpath.jl"))
+
+using IntervalArith
+
+@testset "DifferentiationInterface" begin
+    @test isempty(detect_ambiguities(ThickNumbers))
+    @test isempty(detect_ambiguities(IntervalArith))
+
+    for backend in (AutoForwardDiff(), )
+        a, b = Interval(1, 2), Interval(0, 0.1)
+        f1(t) = a + t*b
+        f2(x) = a + abs2(x)/2
+
+        df1(t) = derivative(f1, backend, t)
+        df2(x) = derivative(f2, backend, x)
+        @test df1(0.5) ≐ b
+        @test df2(b) ⩪ b
+        ddf2(x) = derivative(df2, backend, x)
+        @test ddf2(b) ≐ 1
+
+        # abs
+        dabs(x) = derivative(abs, backend, x)
+        ddabs(x) = derivative(dabs, backend, x)
+        dddabs(x) = derivative(ddabs, backend, x)
+        @test dabs(Interval(1.0, 2.0)) === Interval(1.0, 1.0)
+        @test ddabs(Interval(1.0, 2.0)) === Interval(0.0, 0.0)
+        @test dddabs(Interval(1.0, 2.0)) === Interval(0.0, 0.0)
+        @test dabs(Interval(-1.0, 2.0)) === Interval(-1.0, 1.0)
+        @test ddabs(Interval(-1.0, 2.0)) === Interval(0.0, Inf)
+        abs3 = dddabs(Interval(-1.0, 2.0))
+        @test abs3 === Interval(-Inf, Inf) || isnan_tn(abs3)
+    end
+end
diff --git a/test/extensions/runtests.jl b/test/extensions/runtests.jl
index 07629ba..0305422 100644
--- a/test/extensions/runtests.jl
+++ b/test/extensions/runtests.jl
@@ -1 +1,2 @@
 include("forwarddiff.jl")
+include("di.jl")