diff --git a/lib/Slic3r/GCode.pm b/lib/Slic3r/GCode.pm
index 8881cf0cd..ae1ea0453 100644
--- a/lib/Slic3r/GCode.pm
+++ b/lib/Slic3r/GCode.pm
@@ -334,41 +334,6 @@ sub travel_to {
     return $gcode;
 }
 
-sub needs_retraction {
-    my ($self, $travel, $role) = @_;
-    
-    if ($travel->length < scale $self->config->get_at('retract_before_travel', $self->writer->extruder->id)) {
-        # skip retraction if the move is shorter than the configured threshold
-        return 0;
-    }
-    
-    if (defined $role && $role == EXTR_ROLE_SUPPORTMATERIAL && $self->layer->as_support_layer->support_islands->contains_polyline($travel)) {
-        # skip retraction if this is a travel move inside a support material island
-        return 0;
-    }
-    
-    if ($self->config->only_retract_when_crossing_perimeters && $self->has_layer) {
-        if ($self->config->fill_density > 0
-            && $self->layer->any_internal_region_slice_contains_polyline($travel)) {
-            # skip retraction if travel is contained in an internal slice *and*
-            # internal infill is enabled (so that stringing is entirely not visible)
-            return 0;
-        } elsif ($self->layer->any_bottom_region_slice_contains_polyline($travel)
-            && defined $self->layer->upper_layer
-            && $self->layer->upper_layer->slices->contains_polyline($travel)
-            && ($self->config->bottom_solid_layers >= 2 || $self->config->fill_density > 0)) {
-            # skip retraction if travel is contained in an *infilled* bottom slice
-            # but only if it's also covered by an *infilled* upper layer's slice
-            # so that it's not visible from above (a bottom surface might not have an
-            # upper slice in case of a thin membrane)
-            return 0;
-        }
-    }
-    
-    # retract if only_retract_when_crossing_perimeters is disabled or doesn't apply
-    return 1;
-}
-
 sub set_extruder {
     my ($self, $extruder_id) = @_;
     
diff --git a/xs/src/libslic3r/GCode.cpp b/xs/src/libslic3r/GCode.cpp
index 9acfe47d3..d7b2fcbfd 100644
--- a/xs/src/libslic3r/GCode.cpp
+++ b/xs/src/libslic3r/GCode.cpp
@@ -1,4 +1,5 @@
 #include "GCode.hpp"
+#include "ExtrusionEntity.hpp"
 
 namespace Slic3r {
 
@@ -213,6 +214,44 @@ GCode::preamble()
     return gcode;
 }
 
+bool
+GCode::needs_retraction(const Polyline &travel, ExtrusionRole role)
+{
+    if (travel.length() < scale_(this->config.retract_before_travel.get_at(this->writer.extruder()->id))) {
+        // skip retraction if the move is shorter than the configured threshold
+        return false;
+    }
+    
+    if (role == erSupportMaterial) {
+        SupportLayer* support_layer = dynamic_cast<SupportLayer*>(this->layer);
+        if (support_layer->support_islands.contains(travel)) {
+            // skip retraction if this is a travel move inside a support material island
+            return false;
+        }
+    }
+    
+    if (this->config.only_retract_when_crossing_perimeters && this->layer != NULL) {
+        if (this->config.fill_density.value > 0
+            && this->layer->any_internal_region_slice_contains(travel)) {
+            /*  skip retraction if travel is contained in an internal slice *and*
+                internal infill is enabled (so that stringing is entirely not visible)  */
+            return false;
+        } else if (this->layer->any_bottom_region_slice_contains(travel)
+            && this->layer->upper_layer != NULL
+            && this->layer->upper_layer->slices.contains(travel)
+            && (this->config.bottom_solid_layers.value >= 2 || this->config.fill_density.value > 0)) {
+            /*  skip retraction if travel is contained in an *infilled* bottom slice
+                but only if it's also covered by an *infilled* upper layer's slice
+                so that it's not visible from above (a bottom surface might not have an
+                upper slice in case of a thin membrane)  */
+            return false;
+        }
+    }
+    
+    // retract if only_retract_when_crossing_perimeters is disabled or doesn't apply
+    return true;
+}
+
 std::string
 GCode::retract(bool toolchange)
 {
diff --git a/xs/src/libslic3r/GCode.hpp b/xs/src/libslic3r/GCode.hpp
index 8b37386e9..2dbbebddb 100644
--- a/xs/src/libslic3r/GCode.hpp
+++ b/xs/src/libslic3r/GCode.hpp
@@ -87,6 +87,7 @@ class GCode {
     void apply_print_config(const PrintConfig &print_config);
     void set_origin(const Pointf &pointf);
     std::string preamble();
+    bool needs_retraction(const Polyline &travel, ExtrusionRole role);
     std::string retract(bool toolchange = false);
     std::string unretract();
     Pointf point_to_gcode(const Point &point);
diff --git a/xs/xsp/GCode.xsp b/xs/xsp/GCode.xsp
index 41bdbc042..fdfc3d894 100644
--- a/xs/xsp/GCode.xsp
+++ b/xs/xsp/GCode.xsp
@@ -152,6 +152,8 @@
     void set_origin(Pointf* pointf)
         %code{% THIS->set_origin(*pointf); %};
     std::string preamble();
+    bool needs_retraction(Polyline* travel, ExtrusionRole role)
+        %code{% RETVAL = THIS->needs_retraction(*travel, role); %};
     std::string retract(bool toolchange = false);
     std::string unretract();
     Clone<Pointf> point_to_gcode(Point* point)