diff --git a/python/README-building-wheels.md b/python/README-building-wheels.md
index 4ae672267..34158d5e1 100644
--- a/python/README-building-wheels.md
+++ b/python/README-building-wheels.md
@@ -1,6 +1,6 @@
 # Building manylinux1 wheels
 
-To cause everything to be rebuilt, this script will delete ALL changes to the
+**WARNING:** To cause everything to be rebuilt, this script will delete ALL changes to the
 repository, including both changes to tracked files, and ANY untracked files.
 
 It will also cause all files inside the repository to be owned by root, and
@@ -9,7 +9,7 @@ produce .whl files owned by root.
 Inside the root directory (i.e., one level above this python directory), run
 
 ```
-docker run --rm -w /ray -v `pwd`:/ray -ti rayproject/arrow_linux_x86_64_base:latest /ray/python/build-wheel-manylinux1.sh
+docker run -e TRAVIS_COMMIT=<commit_number_to_use> --rm -w /ray -v `pwd`:/ray -ti rayproject/arrow_linux_x86_64_base:python-3.8.0 /ray/python/build-wheel-manylinux1.sh
 ```
 
 The wheel files will be placed in the .whl directory.