diff --git a/time/exp_xform.jl b/time/exp_xform.jl
index 7d5cb07f..86063478 100644
--- a/time/exp_xform.jl
+++ b/time/exp_xform.jl
@@ -8,7 +8,7 @@ using BenchmarkTools: @btime
 
 
 # timing test
-function exp_xform_time( ; T::DataType = ComplexF32)
+function exp_xform_time( ; T::Type{<:Complex{<:AbstractFloat}} = ComplexF32)
 
     modes = (:element, :row, :column)