diff --git a/noxfile.py b/noxfile.py
index d1d3acaa0..f69ee5de7 100644
--- a/noxfile.py
+++ b/noxfile.py
@@ -144,7 +144,7 @@ def docs(session):
     """Build the docs for this library."""
 
     session.install("-e", ".")
-    session.install("sphinx", "alabaster", "recommonmark")
+    session.install("sphinx<3.0.0", "jinja2<3.1", "alabaster", "recommonmark")
 
     shutil.rmtree(os.path.join("docs", "_build"), ignore_errors=True)
     session.run(
diff --git a/setup.py b/setup.py
index fb083f03a..a10fb1c91 100644
--- a/setup.py
+++ b/setup.py
@@ -35,6 +35,7 @@
     "google-api-core[grpc] >= 1.31.5, <3.0.0dev,!=2.0.*,!=2.1.*,!=2.2.*,!=2.3.0",
     "grpc-google-iam-v1 >= 0.12.3, < 0.13dev",
     'enum34; python_version < "3.4"',
+    "protobuf<4.0.0dev",
 ]
 extras = {}