diff --git a/lib/Slic3r/Layer.pm b/lib/Slic3r/Layer.pm
index bc65064a9..4a2c89689 100644
--- a/lib/Slic3r/Layer.pm
+++ b/lib/Slic3r/Layer.pm
@@ -3,7 +3,7 @@ use Moo;
 
 use Slic3r::Geometry::Clipper qw(union_ex);
 
-has 'id'                => (is => 'rw', required => 1); # sequential number of layer, 0-based
+has 'id'                => (is => 'rw', required => 1, trigger => 1); # sequential number of layer, 0-based
 has 'object'            => (is => 'ro', weak_ref => 1, required => 1);
 has 'regions'           => (is => 'ro', default => sub { [] });
 has 'slicing_errors'    => (is => 'rw');
@@ -20,6 +20,11 @@ has 'slices'            => (is => 'rw');
 # ordered collection of extrusion paths to fill surfaces for support material
 has 'support_fills'     => (is => 'rw');
 
+sub _trigger_id {
+    my $self = shift;
+    $_->_trigger_layer for @{$self->regions || []};
+}
+
 # Z used for slicing
 sub _build_slice_z {
     my $self = shift;
diff --git a/lib/Slic3r/Layer/Region.pm b/lib/Slic3r/Layer/Region.pm
index c5dc43051..dd16c17d0 100644
--- a/lib/Slic3r/Layer/Region.pm
+++ b/lib/Slic3r/Layer/Region.pm
@@ -11,11 +11,12 @@ has 'layer' => (
     is          => 'ro',
     weak_ref    => 1,
     required    => 1,
+    trigger     => 1,
     handles     => [qw(id slice_z print_z height flow)],
 );
 has 'region'            => (is => 'ro', required => 1);
-has 'perimeter_flow'    => (is => 'lazy');
-has 'infill_flow'       => (is => 'lazy');
+has 'perimeter_flow'    => (is => 'rw');
+has 'infill_flow'       => (is => 'rw');
 
 # collection of spare segments generated by slicing the original geometry;
 # these need to be merged in continuos (closed) polylines
@@ -47,18 +48,16 @@ has 'perimeters' => (is => 'rw', default => sub { [] });
 # ordered collection of extrusion paths to fill surfaces
 has 'fills' => (is => 'rw', default => sub { [] });
 
-sub _build_perimeter_flow {
+sub _trigger_layer {
     my $self = shift;
-    return $self->id == 0
+    
+    $self->perimeter_flow($self->id == 0
         ? $self->region->first_layer_flows->{perimeter}
-        : $self->region->flows->{perimeter}
-}
-
-sub _build_infill_flow {
-    my $self = shift;
-    return $self->id == 0
+        : $self->region->flows->{perimeter});
+    
+    $self->infill_flow($self->id == 0
         ? $self->region->first_layer_flows->{infill}
-        : $self->region->flows->{infill}
+        : $self->region->flows->{infill});
 }
 
 # build polylines from lines