diff --git a/tests/xtimer_mutex_lock_timeout/tests/01-run.py b/tests/xtimer_mutex_lock_timeout/tests/01-run.py
index 14170f10dd..dd630eb1aa 100755
--- a/tests/xtimer_mutex_lock_timeout/tests/01-run.py
+++ b/tests/xtimer_mutex_lock_timeout/tests/01-run.py
@@ -29,14 +29,17 @@ def testfunc(child):
     child.expect_exact("> ")
     child.sendline("mutex_timeout_long_locked_low")
     child.expect("starting test: xtimer mutex lock timeout with thread")
-    child.expect("threads = 2")
+    child.expect("threads = (\d+)")
+    num_threads = int(child.match.group(1))
     child.expect("THREAD low prio: start")
     child.expect("MAIN THREAD: calling xtimer_mutex_lock_timeout")
     child.expect("OK")
-    child.expect("threads = 3")
+    child.expect("threads = (\d+)")
+    assert int(child.match.group(1)) == num_threads + 1
     child.expect("MAIN THREAD: waiting for created thread to end")
     child.expect("THREAD low prio: exiting low")
-    child.expect("threads = 2")
+    child.expect("threads = (\d+)")
+    assert int(child.match.group(1)) == num_threads
     child.expect_exact("> ")
     child.sendline("mutex_timeout_short_locked")
     child.expect("starting test: xtimer mutex lock timeout with short timeout and locked mutex")