diff --git a/setup.py b/setup.py
index c58c99d8f..8fbd48d07 100644
--- a/setup.py
+++ b/setup.py
@@ -37,7 +37,7 @@ setup(
         'envparse',
         'jsonrpc',
         'cryptography',
-        'protobuf',
+        'protobuf==3.6.1',
         'jsonschema',
         'ecdsa',
         'torba',