diff --git a/FHEM/10_MAX.pm b/FHEM/10_MAX.pm
index 0602ebc53..7fafcf377 100755
--- a/FHEM/10_MAX.pm
+++ b/FHEM/10_MAX.pm
@@ -370,7 +370,7 @@ MAX_Parse($$)
     #The HeatingThermostat uses the measurementOffset during control
     #but does not apply it to measuredTemperature before sending it to us
     my $measOffset = ReadingsVal($shash->{NAME},"measurementOffset","");
-    $measuredTemperature += $measOffset if($measuredTemperature ne "" and $measOffset ne "");
+    $measuredTemperature -= $measOffset if($measuredTemperature ne "" and $measOffset ne "");
 
     $shash->{mode} = $mode;
     $shash->{rferror} = $rferror;
@@ -538,7 +538,7 @@ MAX_Parse($$)
     <li>comfortTemperature &lt;value&gt;<br>
       For devices of type HeatingThermostat only. Writes the given comfort temperature to the device's memory. It can be activated by pressing the rightmost physical button on the device.</li>
     <li>measurementOffset &lt;value&gt;<br>
-      For devices of type HeatingThermostat only. Writes the given temperature offset to the device's memory. The thermostat tries to match desiredTemperature to (measured temperature at sensor + measurementOffset). Usually, the measured temperature is a bit higher than the overall room temperature (due to closeness to the heater), so one uses a small negative offset. Must be between -3.5 and 3.5 degree.</li>
+      For devices of type HeatingThermostat only. Writes the given temperature offset to the device's memory. The thermostat tries to match desiredTemperature to (measured temperature at sensor - measurementOffset). Usually, the measured temperature is a bit higher than the overall room temperature (due to closeness to the heater), so one uses a small positive offset. Must be between -3.5 and 3.5 degree.</li>
     <li>minimumTemperature &lt;value&gt;<br>
       For devices of type HeatingThermostat only. Writes the given minimum temperature to the device's memory. It confines the temperature that can be manually set on the device.</li>
     <li>maximumTemperature &lt;value&gt;<br>