diff --git a/lib/denko/sensor/hcsr04.rb b/lib/denko/sensor/hcsr04.rb
index 56a5cd4..82c7558 100644
--- a/lib/denko/sensor/hcsr04.rb
+++ b/lib/denko/sensor/hcsr04.rb
@@ -15,6 +15,9 @@ def initialize_pins(options={})
       def after_initialize(options={})
         super(options)
 
+        # Avoid generating extraneous alerts when used with Denko::PiBoard.
+        echo.stop
+
         # Receive values from echo pin.
         echo.add_callback { |data| self.update(data) }
       end