diff --git a/mycodo/outputs/pump_mcp23017.py b/mycodo/outputs/pump_mcp23017.py
index 6e81731e3..1c4cd2955 100644
--- a/mycodo/outputs/pump_mcp23017.py
+++ b/mycodo/outputs/pump_mcp23017.py
@@ -304,6 +304,9 @@ def output_switch(self, state, output_type=None, amount=None, output_channel=Non
             self.logger.error("Amount cannot be less than 0")
             return
 
+        if output_channel not in self.currently_dispensing:
+            self.currently_dispensing[output_channel] = False
+
         self.logger.debug(f"state: {state}, output_type: {output_type}, amount: {amount}")
 
         if state == 'off':