diff --git a/src/ifcopenshell-python/ifcopenshell/validate.py b/src/ifcopenshell-python/ifcopenshell/validate.py
index 22e0346eb6..4e1ed8e864 100644
--- a/src/ifcopenshell-python/ifcopenshell/validate.py
+++ b/src/ifcopenshell-python/ifcopenshell/validate.py
@@ -14,6 +14,7 @@ attribute        = ifcopenshell.ifcopenshell_wrapper.attribute
 class ValidationError(Exception): pass
 
 simple_type_python_mapping = {
+    # @todo should include unicode for Python2
     "string": str,
     "integer": int,
     "real": float,