diff --git a/lib/Slic3r/Print/Object.pm b/lib/Slic3r/Print/Object.pm
index 537817f52..e4e011960 100644
--- a/lib/Slic3r/Print/Object.pm
+++ b/lib/Slic3r/Print/Object.pm
@@ -57,7 +57,16 @@ sub slice {
             # plus the extra distance required by the support material logic
             my $first_layer_height = $self->config->get_value('first_layer_height');
             $print_z += $first_layer_height;
-            $print_z += $self->config->layer_height * ($self->config->raft_layers - 1);
+            
+            # use a large height
+            my $support_material_layer_height;
+            {
+                my @nozzle_diameters = (
+                    map $self->print->config->get_at('nozzle_diameter', $_), @{$self->print->support_material_extruders}
+                );
+                $support_material_layer_height = 0.75 * min(@nozzle_diameters);
+            }
+            $print_z += $support_material_layer_height * ($self->config->raft_layers - 1);
         
             # compute the average of all nozzles used for printing the object
             my $nozzle_diameter;
diff --git a/xs/src/libslic3r/Print.cpp b/xs/src/libslic3r/Print.cpp
index 0dab8e70b..6fff54720 100644
--- a/xs/src/libslic3r/Print.cpp
+++ b/xs/src/libslic3r/Print.cpp
@@ -322,11 +322,10 @@ Print::object_extruders() const
 
 // returns 0-based indices of used extruders
 std::set<size_t>
-Print::extruders() const
+Print::support_material_extruders() const
 {
-    std::set<size_t> extruders = this->object_extruders();
+    std::set<size_t> extruders;
     
-    // add support material extruder(s)
     FOREACH_OBJECT(this, object) {
         if ((*object)->has_support_material()) {
             extruders.insert((*object)->config.support_material_extruder - 1);
@@ -337,6 +336,18 @@ Print::extruders() const
     return extruders;
 }
 
+// returns 0-based indices of used extruders
+std::set<size_t>
+Print::extruders() const
+{
+    std::set<size_t> extruders = this->object_extruders();
+    
+    std::set<size_t> s_extruders = this->support_material_extruders();
+    extruders.insert(s_extruders.begin(), s_extruders.end());
+    
+    return extruders;
+}
+
 void
 Print::_simplify_slices(double distance)
 {
diff --git a/xs/src/libslic3r/Print.hpp b/xs/src/libslic3r/Print.hpp
index 489eebc08..8252fe2d2 100644
--- a/xs/src/libslic3r/Print.hpp
+++ b/xs/src/libslic3r/Print.hpp
@@ -199,6 +199,7 @@ class Print
     Flow skirt_flow() const;
     
     std::set<size_t> object_extruders() const;
+    std::set<size_t> support_material_extruders() const;
     std::set<size_t> extruders() const;
     void _simplify_slices(double distance);
     double max_allowed_layer_height() const;
diff --git a/xs/xsp/Print.xsp b/xs/xsp/Print.xsp
index 1a6635c30..b1396efe0 100644
--- a/xs/xsp/Print.xsp
+++ b/xs/xsp/Print.xsp
@@ -169,6 +169,14 @@ _constant()
                 RETVAL.push_back(*e);
             }
         %};
+    std::vector<int> support_material_extruders()
+        %code%{
+            std::set<size_t> extruders = THIS->support_material_extruders();
+            RETVAL.reserve(extruders.size());
+            for (std::set<size_t>::const_iterator e = extruders.begin(); e != extruders.end(); ++e) {
+                RETVAL.push_back(*e);
+            }
+        %};
     std::vector<int> extruders()
         %code%{
             std::set<size_t> extruders = THIS->extruders();