diff --git a/DifferentiationInterface/test/runtests.jl b/DifferentiationInterface/test/runtests.jl
index 5391caffb..8a4c3dd52 100644
--- a/DifferentiationInterface/test/runtests.jl
+++ b/DifferentiationInterface/test/runtests.jl
@@ -20,12 +20,14 @@ GROUP = get(ENV, "JULIA_DI_TEST_GROUP", "All")
 
 function subtest(category, folder)
     Pkg.activate(joinpath(@__DIR__, category, folder))
-    Pkg.instantiate()
-    @testset "$file" for file in readdir(joinpath(@__DIR__, category, folder))
+    @testset "$file" for file in filter(
+        endswith(".jl"), readdir(joinpath(@__DIR__, category, folder))
+    )
         @info "Testing category/$folder/$file"
         include(joinpath(@__DIR__, category, folder, file))
     end
-    return Pkg.activate(TEST_ENV)
+    Pkg.activate(TEST_ENV)
+    return nothing
 end
 
 @testset verbose = true "DifferentiationInterface.jl" begin