diff --git a/nrf5/modules/test.py b/nrf5/modules/test.py
index db1af5af88..87af84edf6 100644
--- a/nrf5/modules/test.py
+++ b/nrf5/modules/test.py
@@ -3,8 +3,8 @@ from machine import PWM
 
 def pulse():
     for i in range(0, 101):
-        p = PWM(0, pin=17, freq=50, duty=i, period=16000)
+        p = PWM(0, pin=17, freq=PWM.FREQ_16MHZ, duty=i, period=16000)
         time.sleep_ms(10)
     for i in range(0, 101):
-        p = PWM(0, pin=17, freq=50, duty=100-i, period=16000)
+        p = PWM(0, pin=17, freq=PWM.FREQ_16MHZ, duty=100-i, period=16000)
         time.sleep_ms(10)