diff --git a/CHANGED b/CHANGED
index da8cb7782..d90f8ad9b 100644
--- a/CHANGED
+++ b/CHANGED
@@ -1,5 +1,6 @@
 # Add changes at the top of the list. Keep it in ASCII, and 80-char wide.
 # Do not insert empty lines here, update check depends on it.
+  - bugfix:  51_MOBILEALERTS.pm: Offlimit for decodeHumidityDecimal added
   - change:  98_MSwitch.pm, update V2.07
   - change:  20_FRM_IN: only update on change (Forum #81815)
   - bugfix: 73_AutoShuttersControl: fix absent Event and ModeDown absent bug
diff --git a/FHEM/51_MOBILEALERTS.pm b/FHEM/51_MOBILEALERTS.pm
index 0140bb7af..9219fb0da 100644
--- a/FHEM/51_MOBILEALERTS.pm
+++ b/FHEM/51_MOBILEALERTS.pm
@@ -1041,7 +1041,9 @@ sub MOBILEALERTS_decodeHumidity($) {
 
 sub MOBILEALERTS_decodeHumidityDecimal($) {
     my ($humidity) = @_;
-    return ( $humidity & 0x3FF ) * 0.1;
+    $humidity = $humidity & 0x3FF;
+    return 9999 if ( $humidity == 1023 );
+    return $humidity * 0.1;
 }
 
 sub MOBILEALERTS_humidityToString($) {