diff --git a/spectrometer.py b/spectrometer.py
index 9a03b35..d3b9b7c 100644
--- a/spectrometer.py
+++ b/spectrometer.py
@@ -3,6 +3,7 @@
 import argparse
 import json
 import sys
+import time
 
 from hpcs6500 import HPCS6500, find_hpcs_port
 
@@ -17,6 +18,7 @@ def measure():
     try:
         dev.identify()
         dev.psu_on()
+        time.sleep(0.5)
         reading = dev.take_reading(psu=False)
     finally:
         dev.psu_off()