diff --git a/armsrc/lfops.c b/armsrc/lfops.c
index 70c6e33b9..59bbb8a62 100644
--- a/armsrc/lfops.c
+++ b/armsrc/lfops.c
@@ -16,6 +16,7 @@
 #include "string.h"
 #include "lfdemod.h"
 #include "lfsampling.h"
+#include "usb_cdc.h"
 
 
 /**
@@ -399,7 +400,7 @@ void SimulateTagLowFrequency(uint16_t period, uint32_t gap, uint8_t ledcontrol)
     for(;;) {
         //wait until SSC_CLK goes HIGH
         while(!(AT91C_BASE_PIOA->PIO_PDSR & GPIO_SSC_CLK)) {
-            if(BUTTON_PRESS()) {
+			if(BUTTON_PRESS() || usb_poll()) {
                 DbpString("Stopped");
                 return;
             }