diff --git a/devtimer.py b/devtimer.py
index 02116ff..93155f3 100755
--- a/devtimer.py
+++ b/devtimer.py
@@ -241,18 +241,38 @@
 def beep():
     print("Beep!")
 
-# Check to see if footswitch got pressed
 
-def monitor_footsw():
+# Callback when footswitch is pressed
+
+def footsw_pressed():
     global RUNNING
 
-    while True:
-        if not wiringpi.digitalRead(FOOTSW):  # Button push pulls down
-            sleep(.030)              # Wait for debounce
-            if not wiringpi.digitalRead(FOOTSW):
-                RUNNING = not RUNNING
+    # Process footswitch press accounting for debounce
 
-        sleep(.100)
+    if time() - footsw_pressed.lastISR >= 0.100:
+        RUNNING = not RUNNING
+        footsw_pressed.lastISR = time()
+
+    if DEBUG:
+        print("Running State: %s" % RUNNING)
+
+
+# Check to see if footswitch got pressed
+
+def footsw_monitor():
+
+    # We store last interrupt service time as a callback global for debounce
+
+    footsw_pressed.lastISR = 0
+
+    # Setup the callback
+
+    wiringpi.wiringPiISR(FOOTSW, wiringpi.GPIO.INT_EDGE_FALLING, footsw_pressed)
+
+    # Run the thread forever waiting for footswitch presses
+
+    while True:
+        sleep(1000)
 
 
 # Update the display with elapsed time
@@ -289,6 +309,7 @@
 
     wiringpi.wiringPiSetupGpio()
     wiringpi.pinMode(FOOTSW, wiringpi.GPIO.INPUT)
+    wiringpi.pinMode(FOOTSW, wiringpi.GPIO.PUD_UP)
 
     # Dim displays in film mode
 
@@ -312,7 +333,7 @@
 
     # Start monitoring for footswitch presses
 
-    Thread(name="MonitorFootSW", target=monitor_footsw).start()
+    Thread(name="MonitorFootSW", target=footsw_monitor).start()
 
     # Start timing, using the selected profile and measured temperature
 
@@ -328,7 +349,6 @@
 
         if DEBUG:
             last = time()
-            print("Running State: %s" % RUNNING)
 
         # If we're not running, don't update elapsed time