diff --git a/conftest.py b/conftest.py
index 450ff10a7..95bca39fc 100644
--- a/conftest.py
+++ b/conftest.py
@@ -27,7 +27,12 @@
 
 from borg.testsuite import has_lchflags, no_lchlfags_because, has_llfuse
 from borg.testsuite.platform import fakeroot_detected
-from borg import xattr
+from borg import xattr, constants
+
+
+def pytest_configure(config):
+    # no fixture-based monkey-patching since star-imports are used for the constants module
+    constants.PBKDF2_ITERATIONS = 1
 
 
 def pytest_report_header(config, startdir):