diff --git a/tests/thread/stress_heap.py b/tests/thread/stress_heap.py
index ac3ebe049..5482a9ac6 100644
--- a/tests/thread/stress_heap.py
+++ b/tests/thread/stress_heap.py
@@ -3,6 +3,10 @@
 #
 # MIT license; Copyright (c) 2016 Damien P. George on behalf of Pycom Ltd
 
+try:
+    import utime as time
+except ImportError:
+    import time
 import _thread
 
 def last(l):
@@ -37,6 +41,6 @@ n_finished = 0
 for i in range(n_thread):
     _thread.start_new_thread(thread_entry, (10000,))
 
-# busy wait for threads to finish
+# wait for threads to finish
 while n_finished < n_thread:
-    pass
+    time.sleep(1)
diff --git a/tests/thread/thread_lock4.py b/tests/thread/thread_lock4.py
index d77aa24ee..2f9d42d6b 100644
--- a/tests/thread/thread_lock4.py
+++ b/tests/thread/thread_lock4.py
@@ -2,6 +2,10 @@
 #
 # MIT license; Copyright (c) 2016 Damien P. George on behalf of Pycom Ltd
 
+try:
+    import utime as time
+except ImportError:
+    import time
 import _thread
 
 def fac(n):
@@ -39,6 +43,7 @@ while True:
     with jobs_lock:
         if len(output) == n_jobs:
             break
+    time.sleep(1)
 
 # sort and print the results
 output.sort(key=lambda x: x[0])
diff --git a/tests/thread/thread_qstr1.py b/tests/thread/thread_qstr1.py
index c0256316e..f4136d964 100644
--- a/tests/thread/thread_qstr1.py
+++ b/tests/thread/thread_qstr1.py
@@ -2,6 +2,10 @@
 #
 # MIT license; Copyright (c) 2016 Damien P. George on behalf of Pycom Ltd
 
+try:
+    import utime as time
+except ImportError:
+    import time
 import _thread
 
 # function to check the interned string
@@ -28,8 +32,8 @@ n_qstr_per_thread = 100 # make 1000 for a more stressful test (uses more heap)
 for i in range(n_thread):
     _thread.start_new_thread(th, (i * n_qstr_per_thread, n_qstr_per_thread))
 
-# busy wait for threads to finish
+# wait for threads to finish
 while n_finished < n_thread:
-    pass
+    time.sleep(1)
 
 print('pass')