diff --git a/contrib/zclassic/requirements.txt b/contrib/zclassic/requirements.txt
index 3911b9d4..dc0ed828 100644
--- a/contrib/zclassic/requirements.txt
+++ b/contrib/zclassic/requirements.txt
@@ -5,7 +5,7 @@ ecdsa==0.13.3
 idna==2.6
 jsonrpclib-pelix==0.3.1
 pbkdf2==1.3
-protobuf==3.5.0.post1
+protobuf==3.15.0
 pyaes==1.6.1
 PySocks==1.6.7
 qrcode==5.3