diff --git a/openflexure_microscope/stage/sangaboard/extensible_serial_instrument.py b/openflexure_microscope/stage/sangaboard/extensible_serial_instrument.py
index 63611627..15d9a4a3 100644
--- a/openflexure_microscope/stage/sangaboard/extensible_serial_instrument.py
+++ b/openflexure_microscope/stage/sangaboard/extensible_serial_instrument.py
@@ -271,7 +271,7 @@ class ExtensibleSerialInstrument(object):
             success = False
             for port_name, _, _ in serial.tools.list_ports.comports(): #loop through serial ports, apparently 256 is the limit?!
                 try:
-                    logging.info("Trying port",port_name)
+                    logging.info("Trying port {}".format(port_name))
                     self.open(port_name)
                     success = True
                     logging.info("Success!")