diff --git a/esp32/src/main.cpp b/esp32/src/main.cpp
index c420665..1319b3f 100644
--- a/esp32/src/main.cpp
+++ b/esp32/src/main.cpp
@@ -714,6 +714,7 @@ void setup() {
   }
   /* read button */
   pinMode(BUTTON, INPUT);
+  pinMode(OUTPUT_PUMP, OUTPUT);
  
   /* Disable Wifi and bluetooth */
   WiFi.mode(WIFI_OFF);