diff --git a/swh/provenance/tests/data/generate_repo.py b/swh/provenance/tests/data/generate_repo.py
index 55afc31..0a2e024 100644
--- a/swh/provenance/tests/data/generate_repo.py
+++ b/swh/provenance/tests/data/generate_repo.py
@@ -1,116 +1,116 @@
 import os
 import pathlib
 import shutil
 from subprocess import PIPE, check_call, check_output
 from typing import Any, Dict, List
 
 import click
 import yaml
 
 
 def clean_wd() -> None:
     _, dirnames, filenames = next(os.walk("."))
     for d in dirnames:
         if not d.startswith(".git"):
             shutil.rmtree(d)
     for f in filenames:
         if not f.startswith(".git"):
             os.unlink(f)
 
 
 def print_ids() -> None:
     revid = check_output(["git", "rev-parse", "HEAD"]).decode().strip()
     ts, msg = (
         check_output(["git", "log", "-1", '--format="%at %s"'])
         .decode()
         .strip()[1:-1]
         .split()
     )
     print(f"{ts}.0 {revid} {msg}")
     print(f"{msg:<5} | {'':>5} | {'':>20} | R {revid} | {ts}.0")
 
     for currentpath, dirnames, filenames in os.walk("."):
         if currentpath == ".":
             output = check_output(["git", "cat-file", "-p", "HEAD"]).decode()
             dirhash = output.splitlines()[0].split()[1]
         else:
             currentpath = currentpath[2:]
             output = check_output(["git", "ls-tree", "HEAD", currentpath]).decode()
             dirhash = output.split()[2]
 
         print(f"{'':>5} | {'':>5} | {currentpath:<20} | D {dirhash} | 0.0")
         for fname in filenames:
             fname = os.path.join(currentpath, fname)
             output = check_output(["git", "ls-tree", "HEAD", fname]).decode()
             fhash = output.split()[2]
             print(f"{'':>5} | {'':>5} | {fname:<20} | C {fhash} | 0.0")
 
         if ".git" in dirnames:
             dirnames.remove(".git")
 
 
 def generate_repo(repo_desc: List[Dict[str, Any]], output_dir: str) -> None:
     check_call(["git", "init", output_dir], stdout=PIPE, stderr=PIPE)
     os.chdir(output_dir)
     os.environ.update(
         {
             "GIT_AUTHOR_NAME": "SWH",
             "GIT_AUTHOR_EMAIL": "contact@softwareheritage.org",
             "GIT_COMMITTER_NAME": "SWH",
             "GIT_COMMITTER_EMAIL": "contact@softwareheritage.org",
         }
     )
 
     for rev_d in repo_desc:
         parents = rev_d.get("parents")
         if parents:
             # move at the proper (first) parent position, if any
             check_call(["git", "checkout", parents[0]], stdout=PIPE)
 
         # give a branch name (the msg) to each commit to make it easier to
         # navigate in history
         check_call(["git", "checkout", "-b", rev_d["msg"]], stdout=PIPE)
 
         if parents and len(parents) > 1:
             # it's a merge
             check_call(["git", "merge", "--no-commit", *parents[1:]], stdout=PIPE)
 
         clean_wd()
         for path, content in rev_d["content"].items():
             p = pathlib.Path(path)
             p.parent.mkdir(parents=True, exist_ok=True)
             p.write_text(content)
         os.environ.update(
             {
                 "GIT_AUTHOR_DATE": str(rev_d["date"]),
                 "GIT_COMMITTER_DATE": str(rev_d["date"]),
             }
         )
         check_call(["git", "add", "."], stdout=PIPE)
         check_call(
             [
                 "git",
                 "commit",
                 "--all",
                 "--allow-empty",
                 "-m",
                 rev_d["msg"],
             ],
             stdout=PIPE,
         )
         print_ids()
 
 
 @click.command(name="generate-repo")
 @click.argument("input-file")
 @click.argument("output-dir")
 @click.option("-C", "--clean-output/--no-clean-output", default=False)
 def main(input_file: str, output_dir: str, clean_output: bool) -> None:
-    repo_desc = yaml.load(open(input_file))
+    repo_desc = yaml.load(open(input_file), Loader=yaml.Loader)
     if clean_output and os.path.exists(output_dir):
         shutil.rmtree(output_dir)
     generate_repo(repo_desc, output_dir)
 
 
 if __name__ == "__main__":
     main()