diff --git a/avr/main.asm b/avr/main.asm
index 4381b93..d3d2791 100644
--- a/avr/main.asm
+++ b/avr/main.asm
@@ -245,6 +245,9 @@ printSendStats:
 #ifdef MODULES_COM
 
 Main_SendValueMsg:
+  lds r16, comAddress                ; do we have an address assigned?
+  tst r16
+  breq sendValueMsg_done             ; no, do nothing
   ; send message for current temp
   lds r22, si7021Flags
   mov r16, r22