diff --git a/trace/nox.py b/trace/nox.py
index 08c69cb85df5..4133913d931b 100644
--- a/trace/nox.py
+++ b/trace/nox.py
@@ -14,6 +14,8 @@
 
 from __future__ import absolute_import
 
+import os
+
 import nox
 
 
@@ -41,7 +43,7 @@ def unit_tests(session, python_version):
         '--cov-config=.coveragerc',
         '--cov-report=',
         '--cov-fail-under=97',
-        'tests/',
+        os.path.join('tests', 'unit'),
         *session.posargs
     )
 
diff --git a/trace/setup.py b/trace/setup.py
index aeeae31756e4..d6759ccb1179 100644
--- a/trace/setup.py
+++ b/trace/setup.py
@@ -10,7 +10,7 @@
 install_requires = [
     'google-gax>=0.15.7, <0.16dev',
     'googleapis-common-protos[grpc]>=1.5.2, <2.0dev',
-    'google-cloud-core >= 0.24.0, < 0.25dev',
+    'google-cloud-core >= 0.26.0, < 0.27dev',
 ]
 
 setup(
diff --git a/trace/tests/unit/test__gax.py b/trace/tests/unit/test__gax.py
index 3f950021b85e..f4b87472e0cf 100644
--- a/trace/tests/unit/test__gax.py
+++ b/trace/tests/unit/test__gax.py
@@ -16,8 +16,6 @@
 
 import mock
 
-from google.cloud._testing import _GAXBaseAPI
-
 
 class _Base(object):
     project = 'PROJECT'