diff --git a/.github/workflows/CI.yml b/.github/workflows/CI.yml
index 1963f83e8..becaaa8f9 100644
--- a/.github/workflows/CI.yml
+++ b/.github/workflows/CI.yml
@@ -31,6 +31,7 @@ jobs:
           - 'integration_testing/array'
           - 'integration_testing/turing'
           - 'integration_testing/temporalgps'
+          - 'interface'
     steps:
       - uses: actions/checkout@v4
       - uses: julia-actions/setup-julia@v1
diff --git a/Project.toml b/Project.toml
index fdff8a624..97adf6111 100644
--- a/Project.toml
+++ b/Project.toml
@@ -1,7 +1,7 @@
 name = "Tapir"
 uuid = "07d77754-e150-4737-8c94-cd238a1fb45b"
 authors = ["Will Tebbutt, Hong Ge, and contributors"]
-version = "0.2.2"
+version = "0.2.3"
 
 [deps]
 ADTypes = "47edcb42-4c32-4615-8424-f2b9edc5f35b"
diff --git a/src/interface.jl b/src/interface.jl
index 3e35018fb..30f7bbb0c 100644
--- a/src/interface.jl
+++ b/src/interface.jl
@@ -8,10 +8,10 @@ ensure that you zero-out the tangent fields of `x` each time.
 """
 function value_and_pullback!!(rule::R, ȳ::T, fx::Vararg{CoDual, N}) where {R, N, T}
     out, pb!! = rule(fx...)
-    @assert _typeof(tangent(out)) == T
-    ty = increment!!(tangent(out), ȳ)
+    @assert _typeof(tangent(out)) == fdata_type(T)
+    increment!!(tangent(out), fdata(ȳ))
     v = copy(primal(out))
-    return v, pb!!(ty, map(tangent, fx)...)
+    return v, pb!!(rdata(ȳ))
 end
 
 """
@@ -48,7 +48,7 @@ use-case, consider pre-allocating the `CoDual`s and calling the other method of
 function.
 """
 function value_and_pullback!!(rule::R, ȳ, fx::Vararg{Any, N}) where {R, N}
-    return value_and_pullback!!(rule, ȳ, map(zero_codual, fx)...)
+    return value_and_pullback!!(rule, ȳ, map(zero_fcodual, fx)...)
 end
 
 """
@@ -57,5 +57,5 @@ end
 Equivalent to `value_and_pullback(rule, 1.0, f, x...)` -- assumes `f` returns a `Float64`.
 """
 function value_and_gradient!!(rule::R, fx::Vararg{Any, N}) where {R, N}
-    return value_and_gradient!!(rule, map(zero_codual, fx)...)
+    return value_and_gradient!!(rule, map(zero_fcodual, fx)...)
 end
diff --git a/test/runtests.jl b/test/runtests.jl
index 42541ad66..359a699ec 100644
--- a/test/runtests.jl
+++ b/test/runtests.jl
@@ -58,6 +58,8 @@ include("front_matter.jl")
         include(joinpath("integration_testing", "turing.jl"))
     elseif test_group == "integration_testing/temporalgps"
         include(joinpath("integration_testing", "temporalgps.jl"))
+    elseif test_group == "interface"
+        include("interface.jl")
     else
         throw(error("test_group=$(test_group) is not recognised"))
     end