diff --git a/tests/extmod/time_ms_us.py b/tests/extmod/time_ms_us.py
index 4d0287da31..135cf1e096 100644
--- a/tests/extmod/time_ms_us.py
+++ b/tests/extmod/time_ms_us.py
@@ -7,8 +7,16 @@ except AttributeError:
 
 utime.sleep_ms(1)
 utime.sleep_us(1)
-print(utime.ticks_diff(utime.ticks_ms(), utime.ticks_ms()) <= 1)
-print(utime.ticks_diff(utime.ticks_us(), utime.ticks_us()) <= 500)
+
+t0 = utime.ticks_ms()
+t1 = utime.ticks_ms()
+print(0 <= utime.ticks_diff(t1, t0) <= 1)
+
+t0 = utime.ticks_us()
+t1 = utime.ticks_us()
+print(0 <= utime.ticks_diff(t1, t0) <= 500)
 
 # ticks_cpu may not be implemented, at least make sure it doesn't decrease
-print(utime.ticks_diff(utime.ticks_cpu(), utime.ticks_cpu()) >= 0)
+t0 = utime.ticks_cpu()
+t1 = utime.ticks_cpu()
+print(utime.ticks_diff(t1, t0) >= 0)