diff --git a/fhem/fhem.pl b/fhem/fhem.pl
index 88d55f4ce..c86d5f40a 100755
--- a/fhem/fhem.pl
+++ b/fhem/fhem.pl
@@ -3708,6 +3708,13 @@ ReadingsTimestamp($$$)
   return $default;
 }
 
+sub
+ReadingsAge($$$)
+{
+  my ($device,$reading,$default) = @_;
+  return time() - time_str2num(ReadingsTimestamp($device,$reading,$default));
+}
+
 sub
 Value($)
 {