diff --git a/requirements.txt b/requirements.txt
index 557e5e1..efc2069 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -32,7 +32,7 @@ matplotlib==2.2.5
 mock==4.0.1
 numpy==1.18.1
 packaging==18.0
-protobuf==3.11.3
+protobuf==3.18.3
 PyHamcrest==2.0.1
 pyparsing==2.4.6
 python-crfsuite==0.9.6