diff --git a/src/ems.h b/src/ems.h
index 891809249..702f1a793 100644
--- a/src/ems.h
+++ b/src/ems.h
@@ -29,7 +29,7 @@
 #define EMS_VALUE_INT_ON 1             // boolean true
 #define EMS_VALUE_INT_OFF 0            // boolean false
 #define EMS_VALUE_INT_NOTSET 0xFF      // for 8-bit ints
-#define EMS_VALUE_SHORT_NOTSET 0xFFFF  // for 2-byte signed shorts
+#define EMS_VALUE_SHORT_NOTSET 0x8000  // for 2-byte signed shorts
 #define EMS_VALUE_LONG_NOTSET 0xFFFFFF // for 3-byte longs
 
 #define EMS_THERMOSTAT_WRITE_YES true