diff --git a/sonoff/xsns_22_sr04.ino b/sonoff/xsns_22_sr04.ino
index 32f09bd20..77ea5e829 100644
--- a/sonoff/xsns_22_sr04.ino
+++ b/sonoff/xsns_22_sr04.ino
@@ -34,7 +34,7 @@ real64_t distance;
 
 NewPing* sonar = NULL;
 
-void Sr04Init()
+void Sr04Init(void)
 {
   sr04_echo_pin = pin[GPIO_SR04_ECHO];
   sr04_trig_pin = pin[GPIO_SR04_TRIG];