diff --git a/setup.py b/setup.py
index 422584d12..ad2bcf68d 100644
--- a/setup.py
+++ b/setup.py
@@ -36,6 +36,10 @@
     "google-resumable-media >= 0.5.0, < 0.6dev",
     "protobuf >= 3.6.0",
     "six >=1.13.0,< 2.0.0dev",
+    # rsa >= 4.1 is not compatible with Python 2
+    # https://github.com/sybrenstuvel/python-rsa/issues/152
+    'rsa <4.1; python_version < "3"',
+    'rsa >=3.1.4, <5; python_version >= "3"',
 ]
 extras = {
     "bqstorage": [