diff --git a/FHEM/10_RESIDENTS.pm b/FHEM/10_RESIDENTS.pm
index fd643af29..c1b0b6a77 100644
--- a/FHEM/10_RESIDENTS.pm
+++ b/FHEM/10_RESIDENTS.pm
@@ -60,6 +60,8 @@ sub RESIDENTS_Define($$) {
 
     Log3 $name, 5, "RESIDENTS $name: called function RESIDENTS_Define()";
 
+    RESIDENTStk_findResidentSlaves($hash);
+
     # set default settings on first define
     if ( $init_done && !defined( $hash->{OLDDEF} ) ) {
         $attr{$name}{alias} = "Residents";
@@ -129,8 +131,6 @@ sub RESIDENTS_Notify($$) {
         && defined( $defs{$devName}{TYPE} )
         && $defs{$devName}{TYPE} =~ /^(ROOMMATE|GUEST|DUMMY)$/ );
 
-    RESIDENTStk_findResidentSlaves($hash);
-
     my @registeredRoommates =
       split( /,/, $hash->{ROOMMATES} )
       if ( defined( $hash->{ROOMMATES} )
@@ -268,15 +268,13 @@ sub RESIDENTS_Set($@) {
     my ( $hash, @a ) = @_;
     my $name = $hash->{NAME};
     my $state = ReadingsVal( $name, "state", "initialized" );
+    my $roommates = ( $hash->{ROOMMATES} ? $hash->{ROOMMATES} : "" );
+    my $guests    = ( $hash->{GUESTS}    ? $hash->{GUESTS}    : "" );
 
     Log3 $name, 5, "RESIDENTS $name: called function RESIDENTS_Set()";
 
     return "No Argument given" if ( !defined( $a[1] ) );
 
-    RESIDENTStk_findResidentSlaves($hash);
-    my $roommates = ( $hash->{ROOMMATES} ? $hash->{ROOMMATES} : "" );
-    my $guests    = ( $hash->{GUESTS}    ? $hash->{GUESTS}    : "" );
-
     # depending on current FHEMWEB instance's allowedCommands,
     # restrict set commands if there is "set-user" in it
     my $adminMode         = 1;
diff --git a/FHEM/20_GUEST.pm b/FHEM/20_GUEST.pm
index b99842021..d1cc6ee68 100644
--- a/FHEM/20_GUEST.pm
+++ b/FHEM/20_GUEST.pm
@@ -131,7 +131,9 @@ sub GUEST_Undefine($$) {
     RESIDENTStk_RemoveInternalTimer( "DurationTimer", $hash );
 
     if ( defined( $hash->{RESIDENTGROUPS} ) ) {
-        foreach ( split( /,/, $hash->{RESIDENTGROUPS} ) ) {
+        my $old = $hash->{RESIDENTGROUPS};
+        delete $hash->{RESIDENTGROUPS};
+        foreach ( split( /,/, $old ) ) {
             RESIDENTStk_findResidentSlaves( $defs{$_} )
               if ( defined( $defs{$_} ) );
         }
diff --git a/FHEM/20_ROOMMATE.pm b/FHEM/20_ROOMMATE.pm
index ce59266d3..599c5d3d8 100644
--- a/FHEM/20_ROOMMATE.pm
+++ b/FHEM/20_ROOMMATE.pm
@@ -136,7 +136,9 @@ sub ROOMMATE_Undefine($$) {
     RESIDENTStk_RemoveInternalTimer( "DurationTimer", $hash );
 
     if ( defined( $hash->{RESIDENTGROUPS} ) ) {
-        foreach ( split( /,/, $hash->{RESIDENTGROUPS} ) ) {
+        my $old = $hash->{RESIDENTGROUPS};
+        delete $hash->{RESIDENTGROUPS};
+        foreach ( split( /,/, $old ) ) {
             RESIDENTStk_findResidentSlaves( $defs{$_} )
               if ( defined( $defs{$_} ) );
         }