diff --git a/swh/lister/opam/lister.py b/swh/lister/opam/lister.py
--- a/swh/lister/opam/lister.py
+++ b/swh/lister/opam/lister.py
@@ -7,7 +7,6 @@
 import logging
 import os
 from subprocess import PIPE, Popen, call
-import tempfile
 from typing import Iterator
 
 from swh.lister.pattern import StatelessLister
@@ -46,12 +45,13 @@
         url: str,
         instance: str,
         credentials: CredentialsType = None,
+        opam_root: str = "/tmp/opam/",
     ):
         super().__init__(
             scheduler=scheduler, credentials=credentials, url=url, instance=instance,
         )
         self.env = os.environ.copy()
-        self.opamroot = tempfile.mkdtemp(prefix="swh_opam_lister")
+        self.opamroot = opam_root
         call(
             [
                 "opam",
diff --git a/swh/lister/opam/tests/test_lister.py b/swh/lister/opam/tests/test_lister.py
--- a/swh/lister/opam/tests/test_lister.py
+++ b/swh/lister/opam/tests/test_lister.py
@@ -4,6 +4,7 @@
 # See top-level LICENSE file for more information
 
 import io
+from tempfile import mkdtemp
 from unittest.mock import MagicMock
 
 from swh.lister.opam.lister import OpamLister
@@ -13,7 +14,12 @@
 
     instance_url = "https://opam.ocaml.org"
 
-    lister = OpamLister(swh_scheduler, url=instance_url, instance="opam")
+    lister = OpamLister(
+        swh_scheduler,
+        url=instance_url,
+        instance="opam",
+        opam_root=mkdtemp(prefix="swh_opam_lister"),
+    )
 
     mocked_popen = MagicMock()
     mocked_popen.stdout = io.BytesIO(b"bar\nbaz\nfoo\n")
@@ -44,7 +50,12 @@
 
     instance_url = f"file://{datadir}/fake_opam_repo"
 
-    lister = OpamLister(swh_scheduler, url=instance_url, instance="fake")
+    lister = OpamLister(
+        swh_scheduler,
+        url=instance_url,
+        instance="fake",
+        opam_root=mkdtemp(prefix="swh_opam_lister"),
+    )
 
     stats = lister.run()