diff --git a/flaschengeist/models/__init__.py b/flaschengeist/models/__init__.py
index 14a36fb..59bb5b5 100644
--- a/flaschengeist/models/__init__.py
+++ b/flaschengeist/models/__init__.py
@@ -1,4 +1,6 @@
+import sys
 import datetime
+
 from sqlalchemy.types import DateTime, TypeDecorator
 
 
@@ -7,6 +9,15 @@ class ModelSerializeMixin:
     Ignores private and protected members as well as members marked as not to publish (name ends with _)
     """
 
+    def __is_optional(self, param):
+        if sys.version_info < (3, 8):
+            return False
+
+        import typing
+        if typing.get_origin(self.__class__.__annotations__[param]) is typing.Union and \
+                typing.get_args(self.__class__.__annotations__[param])[1] is None:
+            return getattr(self, param) is None
+
     def serialize(self):
         """Serialize class to dict
         Returns:
@@ -15,7 +26,7 @@ class ModelSerializeMixin:
         d = {
             param: getattr(self, param)
             for param in self.__class__.__annotations__
-            if not param.startswith("_") and not param.endswith("_")
+            if not param.startswith("_") and not param.endswith("_") and not self.__is_optional(param)
         }
         if len(d) == 1:
             key, value = d.popitem()