diff --git a/ohmpi/hardware_system.py b/ohmpi/hardware_system.py
index edd3b8a94f137bd28493d05a2ec8d1a7cf534819..2f19375c38731d9acc53bf1b7197f0246e3d20fd 100644
--- a/ohmpi/hardware_system.py
+++ b/ohmpi/hardware_system.py
@@ -23,7 +23,7 @@ rx_module = importlib.import_module(f'ohmpi.hardware_components.{HARDWARE_CONFIG
 
 MUX_DEFAULT = HARDWARE_CONFIG['mux']['default']
 MUX_CONFIG = HARDWARE_CONFIG['mux']['boards']
-for k, v in HARDWARE_CONFIG.items():
+for k, v in MUX_CONFIG.items():
     MUX_CONFIG[k].update({'id': k})
     for k2, v2 in MUX_DEFAULT.items():
         MUX_CONFIG[k].update({k2: MUX_CONFIG[k].pop(k2, v2)})