diff --git a/system_tests/vision.py b/system_tests/vision.py
index 6388b4bb8600..62fae6de14ea 100644
--- a/system_tests/vision.py
+++ b/system_tests/vision.py
@@ -73,8 +73,8 @@ def _assert_likelihood(self, likelihood):
                   Likelihood.VERY_UNLIKELY]
         self.assertIn(likelihood, levels)
 
-    def _maybe_http_skip(self, message):
-        if not Config.CLIENT._use_gax:
+    def _pb_not_implemented_skip(self, message):
+        if Config.CLIENT._use_gax:
             self.skipTest(message)
 
 
@@ -195,7 +195,6 @@ def _assert_face(self, face):
 
     def test_detect_faces_content(self):
         client = Config.CLIENT
-        self._maybe_http_skip('gRPC is required for face detection.')
         with open(FACE_FILE, 'rb') as image_file:
             image = client.image(content=image_file.read())
         faces = image.detect_faces()
@@ -204,7 +203,6 @@ def test_detect_faces_content(self):
             self._assert_face(face)
 
     def test_detect_faces_gcs(self):
-        self._maybe_http_skip('gRPC is required for face detection.')
         bucket_name = Config.TEST_BUCKET.name
         blob_name = 'faces.jpg'
         blob = Config.TEST_BUCKET.blob(blob_name)
@@ -221,7 +219,6 @@ def test_detect_faces_gcs(self):
             self._assert_face(face)
 
     def test_detect_faces_filename(self):
-        self._maybe_http_skip('gRPC is required for face detection.')
         client = Config.CLIENT
         image = client.image(filename=FACE_FILE)
         faces = image.detect_faces()
@@ -296,7 +293,7 @@ class TestVisionClientLandmark(BaseVisionTestCase):
     DESCRIPTIONS = ('Mount Rushmore',)
 
     def setUp(self):
-        Config.CLIENT = vision.Client(use_gax=True)
+        Config.CLIENT = vision.Client()
         self.to_delete_by_case = []
 
     def tearDown(self):
@@ -353,7 +350,7 @@ def test_detect_landmark_filename(self):
 
 class TestVisionClientSafeSearch(BaseVisionTestCase):
     def setUp(self):
-        Config.CLIENT = vision.Client(use_gax=False)
+        Config.CLIENT = vision.Client()
         self.to_delete_by_case = []
 
     def tearDown(self):
@@ -370,7 +367,8 @@ def _assert_safe_search(self, safe_search):
         self._assert_likelihood(safe_search.violence)
 
     def test_detect_safe_search_content(self):
-        self._maybe_http_skip('gRPC is required for safe search detection.')
+        self._pb_not_implemented_skip(
+            'gRPC not implemented for safe search detection.')
         client = Config.CLIENT
         with open(FACE_FILE, 'rb') as image_file:
             image = client.image(content=image_file.read())
@@ -380,7 +378,8 @@ def test_detect_safe_search_content(self):
         self._assert_safe_search(safe_search)
 
     def test_detect_safe_search_gcs(self):
-        self._maybe_http_skip('gRPC is required for safe search detection.')
+        self._pb_not_implemented_skip(
+            'gRPC not implemented for safe search detection.')
         bucket_name = Config.TEST_BUCKET.name
         blob_name = 'faces.jpg'
         blob = Config.TEST_BUCKET.blob(blob_name)
@@ -398,7 +397,8 @@ def test_detect_safe_search_gcs(self):
         self._assert_safe_search(safe_search)
 
     def test_detect_safe_search_filename(self):
-        self._maybe_http_skip('gRPC is required for safe search detection.')
+        self._pb_not_implemented_skip(
+            'gRPC not implemented for safe search detection.')
         client = Config.CLIENT
         image = client.image(filename=FACE_FILE)
         safe_searches = image.detect_safe_search()
@@ -470,7 +470,7 @@ def test_detect_text_filename(self):
 
 class TestVisionClientImageProperties(BaseVisionTestCase):
     def setUp(self):
-        Config.CLIENT = vision.Client(use_gax=False)
+        Config.CLIENT = vision.Client()
         self.to_delete_by_case = []
 
     def tearDown(self):
@@ -497,7 +497,8 @@ def _assert_properties(self, image_property):
             self.assertNotEqual(color_info.score, 0.0)
 
     def test_detect_properties_content(self):
-        self._maybe_http_skip('gRPC is required for text detection.')
+        self._pb_not_implemented_skip(
+            'gRPC not implemented for text detection.')
         client = Config.CLIENT
         with open(FACE_FILE, 'rb') as image_file:
             image = client.image(content=image_file.read())
@@ -507,7 +508,8 @@ def test_detect_properties_content(self):
         self._assert_properties(image_property)
 
     def test_detect_properties_gcs(self):
-        self._maybe_http_skip('gRPC is required for text detection.')
+        self._pb_not_implemented_skip(
+            'gRPC not implemented for text detection.')
         client = Config.CLIENT
         bucket_name = Config.TEST_BUCKET.name
         blob_name = 'faces.jpg'
@@ -525,7 +527,8 @@ def test_detect_properties_gcs(self):
         self._assert_properties(image_property)
 
     def test_detect_properties_filename(self):
-        self._maybe_http_skip('gRPC is required for text detection.')
+        self._pb_not_implemented_skip(
+            'gRPC not implemented for text detection.')
         client = Config.CLIENT
         image = client.image(filename=FACE_FILE)
         properties = image.detect_properties()
diff --git a/vision/google/cloud/vision/client.py b/vision/google/cloud/vision/client.py
index f41eedb345b7..89d9829d16fa 100644
--- a/vision/google/cloud/vision/client.py
+++ b/vision/google/cloud/vision/client.py
@@ -58,7 +58,7 @@ class Client(JSONClient):
     _vision_api_internal = None
 
     def __init__(self, project=None, credentials=None, http=None,
-                 use_gax=False):
+                 use_gax=None):
         super(Client, self).__init__(
             project=project, credentials=credentials, http=http)
         self._connection = Connection(