diff --git a/QGL/config.py b/QGL/config.py
index 4a385cd9..20c54afc 100644
--- a/QGL/config.py
+++ b/QGL/config.py
@@ -12,7 +12,7 @@
 
 # plotting options
 plotBackground       = '#EAEAF2'
-gridColor            = []
+gridColor            = None
 
 # select pulse library (standard or all90)
 pulse_primitives_lib = "standard"