diff --git a/lib/Slic3r/ExtrusionPath.pm b/lib/Slic3r/ExtrusionPath.pm
index 20c7930ed..0c324ab09 100644
--- a/lib/Slic3r/ExtrusionPath.pm
+++ b/lib/Slic3r/ExtrusionPath.pm
@@ -5,8 +5,8 @@ use warnings;
 use parent qw(Exporter);
 
 our @EXPORT_OK = qw(EXTR_ROLE_PERIMETER EXTR_ROLE_EXTERNAL_PERIMETER EXTR_ROLE_OVERHANG_PERIMETER
-    EXTR_ROLE_FILL EXTR_ROLE_SOLIDFILL EXTR_ROLE_TOPSOLIDFILL EXTR_ROLE_BRIDGE 
-    EXTR_ROLE_SKIRT EXTR_ROLE_SUPPORTMATERIAL EXTR_ROLE_GAPFILL);
+    EXTR_ROLE_FILL EXTR_ROLE_SOLIDFILL EXTR_ROLE_TOPSOLIDFILL EXTR_ROLE_GAPFILL EXTR_ROLE_BRIDGE 
+    EXTR_ROLE_SKIRT EXTR_ROLE_SUPPORTMATERIAL EXTR_ROLE_SUPPORTMATERIAL_INTERFACE);
 our %EXPORT_TAGS = (roles => \@EXPORT_OK);
 
 1;
diff --git a/lib/Slic3r/Print/SupportMaterial.pm b/lib/Slic3r/Print/SupportMaterial.pm
index 09973f8f3..0a5ba7222 100644
--- a/lib/Slic3r/Print/SupportMaterial.pm
+++ b/lib/Slic3r/Print/SupportMaterial.pm
@@ -608,7 +608,7 @@ sub generate_toolpaths {
             my $mm3_per_mm = $interface_flow->mm3_per_mm($layer->height);
             @loops = map Slic3r::ExtrusionPath->new(
                 polyline    => $_,
-                role        => EXTR_ROLE_SUPPORTMATERIAL,
+                role        => EXTR_ROLE_SUPPORTMATERIAL_INTERFACE,
                 mm3_per_mm  => $mm3_per_mm,
                 width       => $interface_flow->width,
                 height      => $layer->height,
@@ -656,7 +656,7 @@ sub generate_toolpaths {
                 
                 push @paths, map Slic3r::ExtrusionPath->new(
                     polyline    => Slic3r::Polyline->new(@$_),
-                    role        => EXTR_ROLE_SUPPORTMATERIAL,
+                    role        => EXTR_ROLE_SUPPORTMATERIAL_INTERFACE,
                     mm3_per_mm  => $mm3_per_mm,
                     width       => $params->{flow}->width,
                     height      => $layer->height,
diff --git a/xs/src/ExtrusionEntity.hpp b/xs/src/ExtrusionEntity.hpp
index 40e939d0e..c1cffa612 100644
--- a/xs/src/ExtrusionEntity.hpp
+++ b/xs/src/ExtrusionEntity.hpp
@@ -23,6 +23,7 @@ enum ExtrusionRole {
     erGapFill,
     erSkirt,
     erSupportMaterial,
+    erSupportMaterialInterface,
 };
 
 /* Special flags describing loop */
diff --git a/xs/xsp/ExtrusionPath.xsp b/xs/xsp/ExtrusionPath.xsp
index c465cc041..df3813d51 100644
--- a/xs/xsp/ExtrusionPath.xsp
+++ b/xs/xsp/ExtrusionPath.xsp
@@ -141,6 +141,7 @@ _constant()
     EXTR_ROLE_GAPFILL                      = erGapFill
     EXTR_ROLE_SKIRT                        = erSkirt
     EXTR_ROLE_SUPPORTMATERIAL              = erSupportMaterial
+    EXTR_ROLE_SUPPORTMATERIAL_INTERFACE    = erSupportMaterialInterface
   PROTOTYPE:
   CODE:
     RETVAL = ix;