diff --git a/src/borg/testsuite/archiver/lock_cmds_test.py b/src/borg/testsuite/archiver/lock_cmds_test.py
index 7727e764f..6ff31a4d2 100644
--- a/src/borg/testsuite/archiver/lock_cmds_test.py
+++ b/src/borg/testsuite/archiver/lock_cmds_test.py
@@ -1,7 +1,6 @@
 import os
 import subprocess
 import sys
-import time
 from pathlib import Path
 
 import pytest
@@ -32,24 +31,25 @@ def test_with_lock(tmp_path):
     command0 = "python3", "-m", "borg", "repo-create", "--encryption=none"
     # Timings must be adjusted so that command1 keeps running while command2 tries to get the lock,
     # so that lock acquisition for command2 fails as the test expects it.
-    lock_wait, execution_time, startup_wait = 2, 4, 1
-    assert lock_wait < execution_time - startup_wait
-    command1 = "python3", "-c", f'import time; print("first command - acquires the lock"); time.sleep({execution_time})'
+    lock_wait = 2
+    command1 = ("python3", "-c", 'import sys; print("first command - acquires the lock", flush=True); sys.stdin.read()')
     command2 = "python3", "-c", 'print("second command - should never get executed")'
     borgwl = "python3", "-m", "borg", "with-lock", f"--lock-wait={lock_wait}"
     popen_options = dict(stdout=subprocess.PIPE, stderr=subprocess.PIPE, text=True, env=env)
     subprocess.run(command0, env=env, check=True, text=True, capture_output=True)
     assert repo_path.exists()
-    with subprocess.Popen([*borgwl, *command1], **popen_options) as p1:
-        time.sleep(startup_wait)  # Wait until p1 is running
+
+    p1_options = popen_options.copy()
+    p1_options["stdin"] = subprocess.PIPE
+    with subprocess.Popen([*borgwl, *command1], **p1_options) as p1:
+        assert "first command" in p1.stdout.readline()  # Wait until p1 is running and has acquired the lock
         # Now try to acquire another lock on the same repository:
         with subprocess.Popen([*borgwl, *command2], **popen_options) as p2:
             out, err_out = p2.communicate()
             assert "second command" not in out  # command2 is "locked out"
             assert "Failed to create/acquire the lock" in err_out
             assert p2.returncode == 73  # LockTimeout: could not acquire the lock, p1 already has it
-        out, err_out = p1.communicate()
-        assert "first command" in out  # command1 was executed and had the lock
+        out, err_out = p1.communicate(input="")  # Unblock command1 and read output
         assert not err_out
         assert p1.returncode == 0