diff --git a/cubesatsim/cubesatsim.h b/cubesatsim/cubesatsim.h
index adb6b68f..cbca9c76 100644
--- a/cubesatsim/cubesatsim.h
+++ b/cubesatsim/cubesatsim.h
@@ -126,6 +126,7 @@
 #define PROMPT_VOLTAGE 9
 #define PROMPT_PAYLOAD 10
 #define PROMPT_TEMP 11
+#define PROMPT_FORMAT 12
 
 #define PAYLOAD_QUERY 1
 #define PAYLOAD_RESET 2