diff --git a/docker/Dockerfile.ci_lint b/docker/Dockerfile.ci_lint
index 61856fff96f4..00599c27f21c 100644
--- a/docker/Dockerfile.ci_lint
+++ b/docker/Dockerfile.ci_lint
@@ -29,7 +29,7 @@ RUN bash /install/ubuntu1804_install_python.sh
 
 RUN apt-get update && apt-get install -y doxygen graphviz
 
-RUN pip3 install cpplint pylint==2.4.4 mypy black
+RUN pip3 install cpplint pylint==2.4.4 mypy black==20.8b1
 
 # java deps for rat
 COPY install/ubuntu_install_java.sh /install/ubuntu_install_java.sh
diff --git a/python/gen_requirements.py b/python/gen_requirements.py
index 6869e4829d98..00dd4643190e 100755
--- a/python/gen_requirements.py
+++ b/python/gen_requirements.py
@@ -195,7 +195,7 @@
     ("astroid", None),
     ("attrs", None),
     ("autodocsumm", None),
-    ("black", None),
+    ("black", "==20.8b1"),
     ("cloudpickle", None),
     ("commonmark", ">=0.7.3"),  # From PR #213.
     ("coremltools", None),