diff --git a/requirements.txt b/requirements.txt
index 1d3ed8c..577a8b3 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1 +1,3 @@
-protobuf~=4.23.0
+# The core is using protobuf 3.3.0 still (3party/protobuf/), so no point to require newer versions.
+# E.g. Ubuntu 24.04 LTS ships with python3-protobuf 3.21.12 and it works fine.
+protobuf~=3.21.0