diff --git a/sonoff/language/cs-CZ.h b/sonoff/language/cs-CZ.h
index 0cf34043b..ca5bb903a 100644
--- a/sonoff/language/cs-CZ.h
+++ b/sonoff/language/cs-CZ.h
@@ -110,6 +110,7 @@
 #define D_IP_ADDRESS "Adresa IP"
 #define D_LIGHT "Světlo"
 #define D_LWT "LWT"
+#define D_MMHG "mmHg"
 #define D_MODULE "Modul"
 #define D_MQTT "MQTT"
 #define D_MULTI_PRESS "několikeré-stisknutí"