diff --git a/requirements.txt b/requirements.txt
index d661897..a17da28 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -13,7 +13,7 @@ googleapis-common-protos==1.5.6
 grpcio==1.18.0
 idna==2.8
 msgpack==0.6.0
-protobuf==3.6.1
+protobuf==3.18.3
 pyasn1==0.4.5
 pyasn1-modules==0.2.3
 python-dateutil==2.7.5