diff --git a/lib/Slic3r/Print/Object.pm b/lib/Slic3r/Print/Object.pm
index 612eb8555..74427e63d 100644
--- a/lib/Slic3r/Print/Object.pm
+++ b/lib/Slic3r/Print/Object.pm
@@ -127,17 +127,30 @@ sub slice {
     
         # make layers taking custom heights into account
         my $print_z = my $slice_z = my $height = my $id = 0;
+        my $first_object_layer_height = -1;
     
         # add raft layers
         if ($self->config->raft_layers > 0) {
+            $id += $self->config->raft_layers;
+        
+            # raise first object layer Z by the thickness of the raft itself
+            # plus the extra distance required by the support material logic
             $print_z += $self->config->get_value('first_layer_height');
             $print_z += $self->config->layer_height * ($self->config->raft_layers - 1);
-            $id += $self->config->raft_layers;
+        
+            # at this stage we don't know which nozzles are actually used for the first layer
+            # so we compute the average of all of them
+            my $nozzle_diameter = sum(@{$self->print->config->nozzle_diameter})/@{$self->print->config->nozzle_diameter};
+            my $distance = Slic3r::Print::SupportMaterial::contact_distance($nozzle_diameter);
+        
+            # force first layer print_z according to the contact distance
+            # (the loop below will raise print_z by such height)
+            $first_object_layer_height = $distance;
         }
     
         # loop until we have at least one layer and the max slice_z reaches the object height
         my $max_z = unscale($self->size->z);
-        while (!@{$self->layers} || ($slice_z - $height) <= $max_z) {
+        while (($slice_z - $height) <= $max_z) {
             # assign the default height to the layer according to the general settings
             $height = ($id == 0)
                 ? $self->config->get_value('first_layer_height')
@@ -153,7 +166,11 @@ sub slice {
                     next;
                 }
             }
-        
+            
+            if ($first_object_layer_height != -1 && !@{$self->layers}) {
+                $height = $first_object_layer_height;
+            }
+            
             $print_z += $height;
             $slice_z += $height/2;
         
diff --git a/lib/Slic3r/Print/SupportMaterial.pm b/lib/Slic3r/Print/SupportMaterial.pm
index d58a05d68..712d09ab0 100644
--- a/lib/Slic3r/Print/SupportMaterial.pm
+++ b/lib/Slic3r/Print/SupportMaterial.pm
@@ -190,7 +190,7 @@ sub contact_area {
                 @{$layer->regions};
             my $nozzle_diameter = sum(@nozzle_diameters)/@nozzle_diameters;
             
-            my $contact_z = $layer->print_z - $nozzle_diameter * 1.5;
+            my $contact_z = $layer->print_z - contact_distance($nozzle_diameter);
             ###$contact_z = $layer->print_z - $layer->height;
             
             # ignore this contact area if it's too low
@@ -739,4 +739,10 @@ sub overlapping_layers {
     } 0..$#$support_z;
 }
 
+# class method
+sub contact_distance {
+    my ($nozzle_diameter) = @_;
+    return $nozzle_diameter * 1.5;
+}
+
 1;
diff --git a/t/support.t b/t/support.t
index a1e7173d9..402ea33e8 100644
--- a/t/support.t
+++ b/t/support.t
@@ -1,4 +1,4 @@
-use Test::More tests => 14;
+use Test::More tests => 15;
 use strict;
 use warnings;
 
@@ -129,4 +129,31 @@ use Slic3r::Test;
         'first object layer is completely supported by raft';
 }
 
+{
+    my $config = Slic3r::Config->new_from_defaults;
+    $config->set('skirts', 0);
+    $config->set('raft_layers', 2);
+    $config->set('layer_height', 0.35);
+    $config->set('first_layer_height', 0.3);
+    $config->set('nozzle_diameter', [0.5]);
+    $config->set('support_material_extruder', 2);
+    $config->set('support_material_interface_extruder', 2);
+    my $print = Slic3r::Test::init_print('20mm_cube', config => $config);
+    my %raft_z = ();  # z => 1
+    my $tool = undef;
+    Slic3r::GCode::Reader->new->parse(Slic3r::Test::gcode($print), sub {
+        my ($self, $cmd, $args, $info) = @_;
+        
+        if ($cmd =~ /^T(\d+)/) {
+            $tool = $1;
+        } elsif ($info->{extruding} && $info->{dist_XY} > 0) {
+            if ($tool == $config->support_material_extruder-1) {
+                $raft_z{$self->Z} = 1;
+            }
+        }
+    });
+    
+    is scalar(keys %raft_z), $config->raft_layers, 'correct number of raft layers is generated';
+}
+
 __END__