diff --git a/control/controllers.py b/control/controllers.py
index d9fdd6c..51ef1b2 100644
--- a/control/controllers.py
+++ b/control/controllers.py
@@ -15,6 +15,7 @@ class Controller():
         self.input          = None
         self.target         = target
         self.range          = warning_range
+        self.input_label    = "WARNING: NO INPUT LABEL SET"
 
         self.reach_period_s      = reach_period_s
         self.refractary_period_s = refractary_period_s