diff --git a/QnetModem.h b/QnetModem.h
index 0ba29fc..c9b69d9 100644
--- a/QnetModem.h
+++ b/QnetModem.h
@@ -81,6 +81,7 @@ typedef struct mmodem_tag {
 		// 0x12U transmission lost
 		// 0x13U transmission end
 	union {
+		unsigned char unused[51];	// this makes room for trailing crap on the header
 		unsigned char ack;			// the type being acknowledged
 		unsigned char mode;			// 0 idle, 1 dstar, 2 dmr, 3 ysf, 99 calibration
 		struct {