diff --git a/python/semantic_kernel/schema/kernel_json_schema_builder.py b/python/semantic_kernel/schema/kernel_json_schema_builder.py
index 5ec519b5b377..ec8dc5bb4cc5 100644
--- a/python/semantic_kernel/schema/kernel_json_schema_builder.py
+++ b/python/semantic_kernel/schema/kernel_json_schema_builder.py
@@ -18,6 +18,7 @@
     dict: "object",
     set: "array",
     tuple: "array",
+    type(None): "null",
     "int": "integer",
     "str": "string",
     "bool": "boolean",