diff --git a/requirements.txt b/requirements.txt
index 23d6cec..cea7fb8 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -11,7 +11,7 @@ merkletools==1.0.3
 more-itertools==4.3.0
 pkg-resources==0.0.0
 pluggy==0.8.0
-protobuf==3.6.1
+protobuf==3.15.0
 py==1.7.0
 pysha3==1.0.2
 pytest==3.9.1