diff --git a/src/emailservice/requirements.txt b/src/emailservice/requirements.txt
index 7b07113..8138771 100644
--- a/src/emailservice/requirements.txt
+++ b/src/emailservice/requirements.txt
@@ -55,7 +55,7 @@ markupsafe==1.1.0
     # via jinja2
 opencensus[stackdriver]==0.1.10
     # via -r requirements.in
-protobuf==3.15.0
+protobuf==3.18.3
     # via
     #   google-api-core
     #   google-cloud-profiler
@@ -85,7 +85,6 @@ six==1.12.0
     #   google-api-python-client
     #   google-auth
     #   grpcio
-    #   protobuf
 uritemplate==3.0.0
     # via google-api-python-client
 urllib3==1.24.2