diff --git a/src/Fields/mapreduce_cuda.jl b/src/Fields/mapreduce_cuda.jl
index c4a8551e31..03ab059be0 100644
--- a/src/Fields/mapreduce_cuda.jl
+++ b/src/Fields/mapreduce_cuda.jl
@@ -60,6 +60,7 @@ function LinearAlgebra.norm(
 )
     if p == 2
         # currently only one which supports structured types
+        # TODO: perform map without allocation new field
         if normalize
             sqrt.(Statistics.mean(LinearAlgebra.norm_sqr.(field)))
         else