diff --git a/cloudevents/sdk/http/event.py b/cloudevents/sdk/http/event.py
index 1e2dd9e9..c7d4b0a8 100644
--- a/cloudevents/sdk/http/event.py
+++ b/cloudevents/sdk/http/event.py
@@ -24,7 +24,7 @@
 
 
 def default_marshaller(content: any):
-    if len(content) == 0:
+    if content is None or len(content) == 0:
         return None
     try:
         return json.dumps(content)
diff --git a/cloudevents/tests/test_http_events.py b/cloudevents/tests/test_http_events.py
index eba7a20f..140fb823 100644
--- a/cloudevents/tests/test_http_events.py
+++ b/cloudevents/tests/test_http_events.py
@@ -401,3 +401,16 @@ def test_cloudevent_repr(specversion):
     # we had issues in the past where event.__repr__() could run but
     # print(event) would fail.
     print(event)
+
+
+@pytest.mark.parametrize("specversion", ["1.0", "0.3"])
+def test_none_data_cloudevent(specversion):
+    event = CloudEvent(
+        {
+            "source": "<my-url>",
+            "type": "issue.example",
+            "specversion": specversion,
+        }
+    )
+    to_binary_http(event)
+    to_structured_http(event)