diff --git a/guh.pri b/guh.pri
index f5fa9dd9..5e5d8401 100644
--- a/guh.pri
+++ b/guh.pri
@@ -2,7 +2,7 @@
 GUH_VERSION_STRING=$$system('dpkg-parsechangelog | sed -n -e "s/^Version: //p"')
 
 # define JSON protocol version
-JSON_PROTOCOL_VERSION=24
+JSON_PROTOCOL_VERSION=25
 
 DEFINES += GUH_VERSION_STRING=\\\"$${GUH_VERSION_STRING}\\\" JSON_PROTOCOL_VERSION=\\\"$${JSON_PROTOCOL_VERSION}\\\"
 
diff --git a/libguh/typeutils.h b/libguh/typeutils.h
index b965034e..bd8c08aa 100644
--- a/libguh/typeutils.h
+++ b/libguh/typeutils.h
@@ -61,6 +61,7 @@ class Types
     Q_ENUMS(StateOperator)
     Q_ENUMS(ValueOperator)
     Q_ENUMS(InputType)
+    Q_ENUMS(Unit)
 
 public:
     enum InputType {
@@ -76,6 +77,45 @@ public:
         InputTypeMacAddress
     };
 
+    enum Unit {
+        UnitSeconds,
+        UnitMinutes,
+        UnitHours,
+        UnitUnixTime,
+        UnitMeterPerSecond,
+        UnitKilometerPerHour,
+        UnitDegree,
+        UnitRadiant,
+        UnitDegreeCelsius,
+        UnitDegreeKelvin,
+        UnitMilliBar,
+        UnitBar,
+        UnitPascal,
+        UnitHectoPascal,
+        UnitAtmosphere,
+        UnitLumen,
+        UnitLux,
+        UnitCandela,
+        UnitMilliMeter,
+        UnitCentiMeter,
+        UnitMeter,
+        UnitKiloMeter,
+        UnitGram,
+        UnitKiloGram,
+        UnitDezibel,
+        UnitKiloByte,
+        UnitMegaByte,
+        UnitGigaByte,
+        UnitTeraByte,
+        UnitMilliWatt,
+        UnitWatt,
+        UnitKiloWatt,
+        UnitKiloWattHour,
+        UnitPercentage,
+        UnitEuro,
+        UnitDollar
+    };
+
     enum ValueOperator {
         ValueOperatorEquals,
         ValueOperatorNotEquals,
@@ -93,5 +133,6 @@ public:
 Q_DECLARE_METATYPE(Types::ValueOperator)
 Q_DECLARE_METATYPE(Types::StateOperator)
 Q_DECLARE_METATYPE(Types::InputType)
+Q_DECLARE_METATYPE(Types::Unit)
 
 #endif // TYPEUTILS_H