diff --git a/samples/client/petstore/python-legacy/tests/test_api_client.py b/samples/client/petstore/python-legacy/tests/test_api_client.py
index 8da54be7ae7a..9baa62120e16 100644
--- a/samples/client/petstore/python-legacy/tests/test_api_client.py
+++ b/samples/client/petstore/python-legacy/tests/test_api_client.py
@@ -96,7 +96,7 @@ def test_select_header_content_type(self):
 
         content_types = []
         content_type = self.api_client.select_header_content_type(content_types)
-        self.assertEqual(content_type, 'application/json')
+        self.assertEqual(content_type, None)
 
         content_types = ['application/json-patch+json', 'application/json']
         content_type = self.api_client.select_header_content_type(content_types,
diff --git a/samples/client/petstore/python/tests/test_api_client.py b/samples/client/petstore/python/tests/test_api_client.py
index 35747c842173..5142a14e0dbb 100644
--- a/samples/client/petstore/python/tests/test_api_client.py
+++ b/samples/client/petstore/python/tests/test_api_client.py
@@ -120,7 +120,7 @@ def test_select_header_content_type(self):
 
         content_types = []
         content_type = self.api_client.select_header_content_type(content_types)
-        self.assertEqual(content_type, 'application/json')
+        self.assertEqual(content_type, None)
 
         content_types = ['application/json-patch+json', 'application/json']
         content_type = self.api_client.select_header_content_type(content_types,
diff --git a/samples/client/petstore/python_disallowAdditionalPropertiesIfNotPresent/tests/test_api_client.py b/samples/client/petstore/python_disallowAdditionalPropertiesIfNotPresent/tests/test_api_client.py
index c249bf1fc5e8..f808905993c4 100644
--- a/samples/client/petstore/python_disallowAdditionalPropertiesIfNotPresent/tests/test_api_client.py
+++ b/samples/client/petstore/python_disallowAdditionalPropertiesIfNotPresent/tests/test_api_client.py
@@ -120,7 +120,7 @@ def test_select_header_content_type(self):
 
         content_types = []
         content_type = self.api_client.select_header_content_type(content_types)
-        self.assertEqual(content_type, 'application/json')
+        self.assertEqual(content_type, None)
 
     def test_sanitize_for_serialization(self):
         # None