diff --git a/converter/xt_usb/config.h b/converter/xt_usb/config.h
index 24bf3c33..917626f8 100644
--- a/converter/xt_usb/config.h
+++ b/converter/xt_usb/config.h
@@ -71,7 +71,9 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
     EICRA |= ((1<<ISC11) |      \
               (0<<ISC10));      \
 } while (0)
+/* clears flag and enables interrupt */
 #define XT_INT_ON()  do {      \
+    EIFR  |= (1<<INTF1);        \
     EIMSK |= (1<<INT1);         \
 } while (0)
 #define XT_INT_OFF() do {      \