Index: firmware/App/Services/SystemCommMessages.c
===================================================================
diff -u -r8defcfa32034c4068b733930c2e8b0989c55daba -rd756f33d33c00c6ed3adddb1a31a2bd03ac1327a
--- firmware/App/Services/SystemCommMessages.c	(.../SystemCommMessages.c)	(revision 8defcfa32034c4068b733930c2e8b0989c55daba)
+++ firmware/App/Services/SystemCommMessages.c	(.../SystemCommMessages.c)	(revision d756f33d33c00c6ed3adddb1a31a2bd03ac1327a)
@@ -104,7 +104,7 @@
     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();
@@ -177,7 +177,7 @@
     // 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;