diff --git a/src/infrasys/base_quantity.py b/src/infrasys/base_quantity.py
index c0f1b86..5a3d9b4 100644
--- a/src/infrasys/base_quantity.py
+++ b/src/infrasys/base_quantity.py
@@ -19,7 +19,7 @@ class BaseQuantity(ureg.Quantity):  # type: ignore
 
     __base_unit__ = None
 
-    def __init_subclass__(cls, **kwargs) -> None:
+    def __init_subclass__(cls, **kwargs):
         if not cls.__base_unit__:
             raise TypeError("__base_unit__ should be defined")
         super().__init_subclass__(**kwargs)
@@ -44,23 +44,23 @@ def __get_pydantic_core_schema__(
 
     # Required for pydantic validation
     @classmethod
-    def validate(cls, value, *_):
+    def validate(cls, value, *_) -> "BaseQuantity":
         if isinstance(value, BaseQuantity):
             if cls.__base_unit__:
                 assert value.check(
                     cls.__base_unit__
                 ), f"Unit must be compatible with {cls.__base_unit__}"
-                return value
+                return cls(value)
         if isinstance(value, pint.Quantity):
             if cls.__base_unit__:
                 assert value.check(
                     cls.__base_unit__
                 ), f"Unit must be compatible with {cls.__base_unit__}"
-                return value
+                return cls(value.magnitude, value.units)
             else:
                 raise ValueError(f"Invalid type for BaseQuantity: {type(value)}")
         if isinstance(value, cls):
-            return value
+            return cls(value)
         return value
 
     @staticmethod
diff --git a/src/infrasys/system.py b/src/infrasys/system.py
index 25a0e80..0e1a1fc 100644
--- a/src/infrasys/system.py
+++ b/src/infrasys/system.py
@@ -1064,7 +1064,6 @@ def _deserialize_fields(
                     values[field] = composed_value
                 elif isinstance(metadata.fields, SerializedQuantityType):
                     quantity_type = cached_types.get_type(metadata.fields)
-                    # values[field] = quantity_type.from_dict(value)
                     values[field] = quantity_type(value=value["value"], units=value["units"])
                 else:
                     msg = f"Bug: unhandled type: {field=} {value=}"