diff --git a/python/lsst/ts/externalscripts/maintel/make_cbp_throughput_scan.py b/python/lsst/ts/externalscripts/maintel/make_cbp_throughput_scan.py
index 366faf30..853054b7 100755
--- a/python/lsst/ts/externalscripts/maintel/make_cbp_throughput_scan.py
+++ b/python/lsst/ts/externalscripts/maintel/make_cbp_throughput_scan.py
@@ -686,7 +686,7 @@ async def take_electrometer_scan(
     async def take_calibration_sequence(self):
         """Take the CBP calibration sequence."""
 
-        calibration_summary = {}
+        calibration_summary = {"steps": []}
         wavelength = float(self.config.wavelength)
         wavelength_width = float(self.config.wavelength_width)
         wavelength_resolution = float(self.config.wavelength_resolution)