diff --git a/setup.py b/setup.py
index 57b7b4e9d0..b640b8b8f5 100644
--- a/setup.py
+++ b/setup.py
@@ -34,6 +34,7 @@
     # https://github.com/googleapis/google-cloud-python/issues/10566
     "google-cloud-core >= 1.4.1, <3.0.0dev",
     "proto-plus >= 1.20.5, <2.0.0dev",
+    "protobuf >= 3.19.0, <4.0.0dev",
 ]
 extras = {}