diff --git a/lib/growth/indicators/load.ex b/lib/growth/indicators/load.ex
index b86af07..c8d6164 100644
--- a/lib/growth/indicators/load.ex
+++ b/lib/growth/indicators/load.ex
@@ -154,7 +154,7 @@ defmodule Growth.Indicators.Load do
           as_float(t)
         end
 
-      key = {String.to_atom(gender), unit, converted_t}
+      key = {String.to_atom(gender), String.to_atom(unit), converted_t}
 
       value = %{
         l: as_float(l),