--- a/build/build-clang/build-clang.py
+++ b/build/build-clang/build-clang.py
@@ -318,19 +318,19 @@ def prune_final_dir_for_clang_tidy(final
     for f in glob.glob("%s/share/clang/*" % final_dir):
         if re_clang_tidy.search(os.path.basename(f)) is None:
             delete(f)
 
 
 if __name__ == "__main__":
     # The directories end up in the debug info, so the easy way of getting
     # a reproducible build is to run it in a know absolute directory.
-    # We use a directory in /builds/slave because the mozilla infrastructure
-    # cleans it up automatically.
-    base_dir = "/builds/slave/moz-toolchain"
+    # We use a directory that is registered as a volume in the Docker image.
+    base_dir = "/builds/worker/workspace/moz-toolchain"
+
     if is_windows():
         # TODO: Because Windows taskcluster builds are run with distinct
         # user IDs for each job, we can't store things in some globally
         # accessible directory: one job will run, checkout LLVM to that
         # directory, and then if another job runs, the new user won't be
         # able to access the previously-checked out code--or be able to
         # delete it.  So on Windows, we build in the task-specific home
         # directory; we will eventually add -fdebug-prefix-map options