diff --git a/noxfile.py b/noxfile.py
index f14f4b8493..b201abc4f8 100644
--- a/noxfile.py
+++ b/noxfile.py
@@ -72,7 +72,7 @@ def lint_setup_py(session):
 
 def default(session):
     # Install all test dependencies, then install this package in-place.
-    session.install("mock", "pytest", "pytest-cov")
+    session.install("mock", "pytest", "pytest-cov", "pytz")
 
     if session.python != "2.7":
         session.install("-e", ".[tracing]")
@@ -128,6 +128,7 @@ def system(session):
 
     # Install all test dependencies, then install this package into the
     # virtualenv's dist-packages.
+
     session.install(
         "mock",
         "pytest",
diff --git a/setup.py b/setup.py
index 8495c20bef..b7941a3742 100644
--- a/setup.py
+++ b/setup.py
@@ -29,8 +29,8 @@
 # 'Development Status :: 5 - Production/Stable'
 release_status = "Development Status :: 5 - Production/Stable"
 dependencies = [
-    "google-api-core[grpc, grpcgcp] >= 1.14.0, < 2.0.0dev",
-    "google-cloud-core >= 1.4.1, < 2.0dev",
+    "google-api-core[grpc, grpcgcp] >= 1.31.5, <3.0.0dev,!=2.0.*,!=2.1.*,!=2.2.*,!=2.3.0",
+    "google-cloud-core >= 1.4.1, < 3.0dev",
     "grpc-google-iam-v1 >= 0.12.3, < 0.13dev",
 ]
 extras = {