diff --git a/pyproject.toml b/pyproject.toml
index a9438c7..1badc33 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -33,7 +33,7 @@ requires-python = ">=3.8"
 dependencies = [
     "pyelftools>=0.29,<1.0",
     "hidapi>=0.7.99",
-    "protobuf >=5",
+    "protobuf>=5.28,<6",
     "pycryptodomex>=3.6.1",
     "future",
     "ecpy>=0.9.0",