diff --git a/requirements.txt b/requirements.txt
index 0fad130..2c91208 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -10,7 +10,7 @@ grpcio==1.27.1
 idna==2.8
 Markdown==3.2
 pkg-resources==0.0.0
-protobuf==3.11.3
+protobuf==3.18.3
 pyasn1==0.4.8
 pyasn1-modules==0.2.8
 python-frontmatter==0.5.0