diff --git a/requirements.txt b/requirements.txt
index 14b039d..cee65fa 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -26,7 +26,7 @@ Jinja2==2.10.3
 MarkupSafe==1.1.1
 msgpack==0.6.2
 nexmo==2.4.0
-protobuf==3.11.2
+protobuf==3.18.3
 pyasn1==0.4.8
 pyasn1-modules==0.2.8
 pycparser==2.19