diff --git a/aredis_om/model/model.py b/aredis_om/model/model.py
index e45e3939..377ededb 100644
--- a/aredis_om/model/model.py
+++ b/aredis_om/model/model.py
@@ -1695,6 +1695,9 @@ async def save(
         self.check()
         db = self._get_db(pipeline)
         document = jsonable_encoder(self.dict())
+
+        # filter out values which are `None` because they are not valid in a HSET
+        document = {k: v for k, v in document.items() if v is not None}
         # TODO: Wrap any Redis response errors in a custom exception?
         await db.hset(self.key(), mapping=document)
         return self
diff --git a/tests/test_hash_model.py b/tests/test_hash_model.py
index 1870ec3d..c9673585 100644
--- a/tests/test_hash_model.py
+++ b/tests/test_hash_model.py
@@ -878,6 +878,26 @@ async def test_xfix_queries(members, m):
 
 
 @py_test_mark_asyncio
+async def test_none():
+    class ModelWithNoneDefault(HashModel):
+        test: Optional[str] = Field(index=True, default=None)
+
+    class ModelWithStringDefault(HashModel):
+        test: Optional[str] = Field(index=True, default="None")
+
+    await Migrator().run()
+
+    a = ModelWithNoneDefault()
+    await a.save()
+    res = await ModelWithNoneDefault.find(ModelWithNoneDefault.pk == a.pk).first()
+    assert res.test is None
+
+    b = ModelWithStringDefault()
+    await b.save()
+    res = await ModelWithStringDefault.find(ModelWithStringDefault.pk == b.pk).first()
+    assert res.test == "None"
+
+
 async def test_update_validation():
     class TestUpdate(HashModel):
         name: str
diff --git a/tests/test_json_model.py b/tests/test_json_model.py
index b1950b6e..84649202 100644
--- a/tests/test_json_model.py
+++ b/tests/test_json_model.py
@@ -974,6 +974,26 @@ async def test_xfix_queries(m):
 
 
 @py_test_mark_asyncio
+async def test_none():
+    class ModelWithNoneDefault(JsonModel):
+        test: Optional[str] = Field(index=True, default=None)
+
+    class ModelWithStringDefault(JsonModel):
+        test: Optional[str] = Field(index=True, default="None")
+
+    await Migrator().run()
+
+    a = ModelWithNoneDefault()
+    await a.save()
+    res = await ModelWithNoneDefault.find(ModelWithNoneDefault.pk == a.pk).first()
+    assert res.test is None
+
+    b = ModelWithStringDefault()
+    await b.save()
+    res = await ModelWithStringDefault.find(ModelWithStringDefault.pk == b.pk).first()
+    assert res.test == "None"
+
+
 async def test_update_validation():
 
     class Embedded(EmbeddedJsonModel):