diff --git a/requirements.txt b/requirements.txt
index b33d485..b16ea1a 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -10,7 +10,7 @@ googleapis-common-protos==1.5.3
 idna==2.6
 Jinja2==2.10
 MarkupSafe==1.0
-protobuf==3.4.0
+protobuf==3.15.0
 pyasn1==0.3.7
 pyasn1-modules==0.1.5
 requests==2.18.4