diff --git a/quad/src/virt_quad/hw_impl_unix_mio7_led.c b/quad/src/virt_quad/hw_impl_unix_mio7_led.c
index b9b66dd09d0725936a97fc86563fb709693b2416..0a7d752fbb70a214fb5c934771244f9b54b602c8 100644
--- a/quad/src/virt_quad/hw_impl_unix_mio7_led.c
+++ b/quad/src/virt_quad/hw_impl_unix_mio7_led.c
@@ -9,7 +9,7 @@
 
 void * output_cached_led();
 
-int on;
+volatile int on;
 static char *led_fifo_name;
 pthread_t worker;