diff --git a/src/Li2.jl b/src/Li2.jl
index bba31b6..908e553 100644
--- a/src/Li2.jl
+++ b/src/Li2.jl
@@ -237,7 +237,8 @@ li2(z::Real) = li2(Complex(z))
 
 _li2(z::ComplexF16) = oftype(z, _li2(ComplexF32(z)))
 
-function _li2(z::Complex{T})::Complex{T} where T
+# overload for complex types for which li2_approx uses pre-computed Bernoulli numbers
+function _li2(z::Complex{T})::Complex{T} where {T<:Union{Float32, Float64}}
     rz, iz = reim(z)
 
     if iszero(iz)
@@ -270,7 +271,8 @@ function _li2(z::Complex{T})::Complex{T} where T
     end
 end
 
-function _li2(z::Complex{BigFloat})::Complex{BigFloat}
+# overload for generic complex types
+function _li2(z::Complex{T})::Complex{T} where T
     rz, iz = reim(z)
 
     if iszero(iz)
diff --git a/test/Dual.jl b/test/Dual.jl
new file mode 100644
index 0000000..ab24ee4
--- /dev/null
+++ b/test/Dual.jl
@@ -0,0 +1,13 @@
+if isdefined(Base, :get_extension)
+    import ForwardDiff
+
+    to_dual(z::Complex) = Complex(ForwardDiff.Dual(real(z)), ForwardDiff.Dual(imag(z)))
+
+    @testset "Dual" begin
+        z = 0.5 + 0.8im
+
+        for n in -10:10
+            @test PolyLog.li(n, to_dual(z)) ≈ PolyLog.li(n, z) rtol=1e-14
+        end
+    end
+end
diff --git a/test/runtests.jl b/test/runtests.jl
index 3740ffd..b9d414f 100644
--- a/test/runtests.jl
+++ b/test/runtests.jl
@@ -9,6 +9,7 @@ include("TestPrecision.jl")
 include("DataReader.jl")
 include("DataTester.jl")
 include("Digamma.jl")
+include("Dual.jl")
 include("Eta.jl")
 include("Factorial.jl")
 include("Harmonic.jl")