Index: firmware/App/Services/SystemCommMessages.c
===================================================================
diff -u -reff31263255b3a3441caff2955b4910f9ccc3656 -ra4f9ac570f88e76b70d2f818cd8f9157e4a83a74
--- firmware/App/Services/SystemCommMessages.c	(.../SystemCommMessages.c)	(revision eff31263255b3a3441caff2955b4910f9ccc3656)
+++ firmware/App/Services/SystemCommMessages.c	(.../SystemCommMessages.c)	(revision a4f9ac570f88e76b70d2f818cd8f9157e4a83a74)
@@ -103,7 +103,7 @@
     data[ msgSize++ ] = MESSAGE_SYNC_BYTE;
 
     // set sequence # and ACK bit (unless this is an ACK to a received message)
-    if ( msg.hdr.msgID != MSG_ID_ACK )
+    if ( msg.hdr.msgID != MSG_ID_ACK_MESSAGE_THAT_REQUIRES_ACK )
     {
         // thread protect next sequence # access & increment
         _disable_IRQ();
@@ -176,7 +176,7 @@
     // send ACK back with same seq. #, but w/o ACK bit
     msg.hdr.seqNo = message->hdr.seqNo * -1;
     // ACK messages always have this ID
-    msg.hdr.msgID = MSG_ID_ACK;
+    msg.hdr.msgID = MSG_ID_ACK_MESSAGE_THAT_REQUIRES_ACK;
     // ACK messages always have no payload
     msg.hdr.payloadLen = 0;