diff --git a/ohmpi/hardware_system.py b/ohmpi/hardware_system.py
index 094b901a76772b25938c2edf37078f07ab66d717..0cd8ec32ff848f7cf62839df3a055e29b2745991 100644
--- a/ohmpi/hardware_system.py
+++ b/ohmpi/hardware_system.py
@@ -93,7 +93,7 @@ class OhmPiHardware:
         self._cabling = kwargs.pop('cabling', {})
         self.mux_boards = {}
         for mux_id, mux_config in HARDWARE_CONFIG['mux'].items():
-            mux_config.pop('model')
+            mux_config.pop('model', '')
             constructor = mux_config.pop('constructor')
             ctl = mux_config.pop('ctl', self.ctl)
             if isinstance(ctl, dict):