diff --git a/swh/loader/mercurial/hgutil.py b/swh/loader/mercurial/hgutil.py
index 189fba9..028e04c 100644
--- a/swh/loader/mercurial/hgutil.py
+++ b/swh/loader/mercurial/hgutil.py
@@ -1,92 +1,104 @@
 # Copyright (C) 2020-2021  The Software Heritage developers
 # See the AUTHORS file at the top-level directory of this distribution
 # License: GNU General Public License version 3, or any later version
 # See top-level LICENSE file for more information
 
 import io
-from multiprocessing import Process, Queue
+import os
+import signal
+import time
 import traceback
 from typing import Dict, NewType
 
+from billiard import Process, Queue
+
 # The internal Mercurial API is not guaranteed to be stable.
 from mercurial import context, error, hg, smartset, util  # type: ignore
 import mercurial.ui  # type: ignore
 
 NULLID = mercurial.node.nullid
 HgNodeId = NewType("HgNodeId", bytes)
 Repository = hg.localrepo
 BaseContext = context.basectx
 LRUCacheDict = util.lrucachedict
 HgSpanSet = smartset._spanset
 HgFilteredSet = smartset.filteredset
 LookupError = error.LookupError
 
 
 def repository(path: str) -> hg.localrepo:
     ui = mercurial.ui.ui.load()
     return hg.repository(ui, path.encode())
 
 
 def branches(repo: hg.localrepo) -> Dict[bytes, HgNodeId]:
     """List repository named branches and their tip node."""
     result = {}
     for tag, heads, tip, isclosed in repo.branchmap().iterbranches():
         if isclosed:
             continue
         result[tag] = tip
     return result
 
 
 class CloneTimeout(Exception):
     pass
 
 
 class CloneFailure(Exception):
     pass
 
 
 def _clone_task(src: str, dest: str, errors: Queue) -> None:
     """Clone task to run in a subprocess.
 
     Args:
         src: clone source
         dest: clone destination
         errors: message queue to communicate errors
     """
     try:
         hg.clone(
             ui=mercurial.ui.ui.load(),
             peeropts={},
             source=src.encode(),
             dest=dest.encode(),
             update=False,
         )
     except Exception as e:
         exc_buffer = io.StringIO()
         traceback.print_exc(file=exc_buffer)
         errors.put_nowait(exc_buffer.getvalue())
         raise e
 
 
-def clone(src: str, dest: str, timeout: int) -> None:
+def clone(src: str, dest: str, timeout: float) -> None:
     """Clone a repository with timeout.
 
     Args:
         src: clone source
         dest: clone destination
         timeout: timeout in seconds
     """
     errors: Queue = Queue()
     process = Process(target=_clone_task, args=(src, dest, errors))
     process.start()
     process.join(timeout)
 
     if process.is_alive():
         process.terminate()
-        process.join(1)
-        if process.is_alive():
-            process.kill()
-        raise CloneTimeout(src, timeout)
+        # Give it a second (literally), then kill it
+        # Can't use `process.join(1)` here, billiard appears to be bugged
+        # https://github.com/celery/billiard/issues/270
+        killed = False
+        for _ in range(10):
+            time.sleep(0.1)
+            if not process.is_alive():
+                break
+        else:
+            killed = True
+            os.kill(process.pid, signal.SIGKILL)
+        raise CloneTimeout(src, timeout, killed)
 
     if not errors.empty():
         raise CloneFailure(src, dest, errors.get())
diff --git a/swh/loader/mercurial/tests/test_hgutil.py b/swh/loader/mercurial/tests/test_hgutil.py
index 3ca3682..3deceff 100644
--- a/swh/loader/mercurial/tests/test_hgutil.py
+++ b/swh/loader/mercurial/tests/test_hgutil.py
@@ -1,46 +1,49 @@
 # Copyright (C) 2020-2021  The Software Heritage developers
 # See the AUTHORS file at the top-level directory of this distribution
 # License: GNU General Public License version 3, or any later version
 # See top-level LICENSE file for more information
-
+import signal
 import time
 import traceback
 
 from mercurial import hg  # type: ignore
 import pytest
 
 from .. import hgutil
 
 
 def test_clone_timeout(monkeypatch):
     src = "https://www.mercurial-scm.org/repo/hello"
     dest = "/dev/null"
-    timeout = 1
+    timeout = 0.1
 
     def clone(*args, **kwargs):
-        time.sleep(5)
+        # ignore SIGTERM to force sigkill
+        signal.signal(signal.SIGTERM, lambda signum, frame: None)
+        time.sleep(2)
 
     monkeypatch.setattr(hg, "clone", clone)
 
     with pytest.raises(hgutil.CloneTimeout) as e:
         hgutil.clone(src, dest, timeout)
-    assert e.value.args == (src, timeout)
+    killed = True
+    assert e.value.args == (src, timeout, killed)
 
 
 def test_clone_error(caplog, tmp_path, monkeypatch):
     src = "https://www.mercurial-scm.org/repo/hello"
     dest = "/dev/null"
     expected_traceback = "Some traceback"
 
     def clone(*args, **kwargs):
         raise ValueError()
 
     def print_exc(file):
         file.write(expected_traceback)
 
     monkeypatch.setattr(hg, "clone", clone)
     monkeypatch.setattr(traceback, "print_exc", print_exc)
 
     with pytest.raises(hgutil.CloneFailure) as e:
         hgutil.clone(src, dest, 1)
     assert e.value.args == (src, dest, expected_traceback)