diff --git a/test/derivative_tests.jl b/test/derivative_tests.jl
index a4eb349b..fd9745de 100644
--- a/test/derivative_tests.jl
+++ b/test/derivative_tests.jl
@@ -133,9 +133,11 @@ end
 
 @testset "Constant Interpolation" begin
     u = [0.0, 2.0, 1.0, 3.0, 2.0, 6.0, 5.5, 5.5, 2.7, 5.1, 3.0]
-    t = collect(0.0:10.0)
+    t = collect(0.0:11.0)
     A = ConstantInterpolation(u, t)
-    @test all(derivative.(Ref(A), t) .== 0.0)
+    t2 = collect(0.0:10.0)
+    @test all(isnan, derivative.(Ref(A), t))
+    @test all(derivative.(Ref(A), t2 .+ 0.1) .== 0.0)
 end
 
 @testset "Quadratic Spline" begin