diff --git a/tests/thread/thread_sleep1.py b/tests/thread/thread_sleep1.py
index 5f7534f6a..032ec1754 100644
--- a/tests/thread/thread_sleep1.py
+++ b/tests/thread/thread_sleep1.py
@@ -3,26 +3,29 @@
 # MIT license; Copyright (c) 2016 Damien P. George on behalf of Pycom Ltd
 
 try:
-    import utime as time
+    import utime
+    sleep_ms = utime.sleep_ms
 except ImportError:
     import time
+    sleep_ms = lambda t: time.sleep(t / 1000)
+
 import _thread
 
 lock = _thread.allocate_lock()
-n_thread = 16
+n_thread = 4
 n_finished = 0
 
 def thread_entry(t):
     global n_finished
-    time.sleep(t)
-    time.sleep(2 * t)
+    sleep_ms(t)
+    sleep_ms(2 * t)
     with lock:
         n_finished += 1
 
 for i in range(n_thread):
-    _thread.start_new_thread(thread_entry, (i / 100,))
+    _thread.start_new_thread(thread_entry, (10 * i,))
 
 # wait for threads to finish
 while n_finished < n_thread:
-    time.sleep(1)
+    sleep_ms(100)
 print('done', n_thread)