diff --git a/ci/conda_env_python.txt b/ci/conda_env_python.txt
index 59e2def1bf3..c26a43f03ed 100644
--- a/ci/conda_env_python.txt
+++ b/ci/conda_env_python.txt
@@ -17,7 +17,7 @@
 
 # don't add pandas here, because it is not a mandatory test dependency
 boto3  # not a direct dependency of s3fs, but needed for our s3fs fixture
-cffi
+cffi<1.16.0  # cffi 1.16.0 with Python 3.9 has an incompatibility with grpcio (required for GCS testbench)
 cython>=0.29.31
 cloudpickle
 fsspec