diff --git a/semantic-text-similarity/requirements.txt b/semantic-text-similarity/requirements.txt
index 64f36c7..04b76a7 100644
--- a/semantic-text-similarity/requirements.txt
+++ b/semantic-text-similarity/requirements.txt
@@ -156,7 +156,7 @@ ply==3.11
 preshed==3.0.2
 prometheus-client==0.5.0
 prompt-toolkit==2.0.7
-protobuf==3.11.3
+protobuf==3.15.0
 psutil==5.4.8
 ptyprocess==0.6.0
 py==1.7.0