diff --git a/requirements.txt b/requirements.txt
index fabdc35..f285659 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -17,7 +17,7 @@ googleapis-common-protos==1.6.0
 grpcio==1.26.0
 idna==2.8
 multidict==4.7.2
-protobuf==3.15.0
+protobuf==3.18.3
 pyasn1==0.4.8
 pyasn1-modules==0.2.7
 pycodestyle==2.5.0