diff --git a/docs/requirements.txt b/docs/requirements.txt
index fb2fdd2..06a8bce 100644
--- a/docs/requirements.txt
+++ b/docs/requirements.txt
@@ -6,3 +6,4 @@ sphinxcontrib-bibtex
 tensorboard
 torch
 tqdm
+protobuf~=3.19.0
diff --git a/setup.py b/setup.py
index 0ae4090..6a1367e 100644
--- a/setup.py
+++ b/setup.py
@@ -22,6 +22,7 @@ def get_install_requires() -> str:
         "torch>=1.4.0",
         "numba>=0.51.0",
         "h5py>=2.10.0",  # to match tensorflow's minimal requirements
+        "protobuf~=3.19.0",  # breaking change, sphinx fail
     ]