diff --git a/Build.PL b/Build.PL
index 6634232a1..3652a080d 100644
--- a/Build.PL
+++ b/Build.PL
@@ -17,7 +17,6 @@ my $build = Module::Build->new(
         'Moo'                       => '0',
         'perl'                      => '5.10.0',
         'Time::HiRes'               => '0',
-        'XXX'                       => '0',
     },
     build_requires => {
         'Test::More' => '0.10',
diff --git a/lib/Slic3r/Extruder.pm b/lib/Slic3r/Extruder.pm
index d64556fd8..53aa60db0 100644
--- a/lib/Slic3r/Extruder.pm
+++ b/lib/Slic3r/Extruder.pm
@@ -34,7 +34,6 @@ has 'speeds' => (
 );
 
 use Slic3r::Geometry qw(points_coincide PI X Y);
-use XXX;
 
 sub change_layer {
     my $self = shift;
diff --git a/lib/Slic3r/ExtrusionLoop.pm b/lib/Slic3r/ExtrusionLoop.pm
index e00954747..1c4c327bb 100644
--- a/lib/Slic3r/ExtrusionLoop.pm
+++ b/lib/Slic3r/ExtrusionLoop.pm
@@ -1,7 +1,6 @@
 package Slic3r::ExtrusionLoop;
 use Moo;
 
-use XXX;
 
 # the underlying Slic3r::Polygon objects holds the geometry
 has 'polygon' => (
diff --git a/lib/Slic3r/ExtrusionPath.pm b/lib/Slic3r/ExtrusionPath.pm
index 77f54ce06..173a05ee2 100644
--- a/lib/Slic3r/ExtrusionPath.pm
+++ b/lib/Slic3r/ExtrusionPath.pm
@@ -2,7 +2,6 @@ package Slic3r::ExtrusionPath;
 use Moo;
 
 use Slic3r::Geometry qw(PI X Y epsilon deg2rad rotate_points);
-use XXX;
 
 # the underlying Slic3r::Polyline objects holds the geometry
 has 'polyline' => (
diff --git a/lib/Slic3r/ExtrusionPath/Collection.pm b/lib/Slic3r/ExtrusionPath/Collection.pm
index ab00e4a10..595e3105d 100644
--- a/lib/Slic3r/ExtrusionPath/Collection.pm
+++ b/lib/Slic3r/ExtrusionPath/Collection.pm
@@ -1,7 +1,6 @@
 package Slic3r::ExtrusionPath::Collection;
 use Moo;
 
-use XXX;
 
 has 'paths' => (
     is      => 'rw',
diff --git a/lib/Slic3r/Fill.pm b/lib/Slic3r/Fill.pm
index 4a496c674..c70dfcce7 100644
--- a/lib/Slic3r/Fill.pm
+++ b/lib/Slic3r/Fill.pm
@@ -15,7 +15,6 @@ use Slic3r::Fill::Rectilinear2;
 use Slic3r::Geometry qw(scale shortest_path);
 use Slic3r::Geometry::Clipper qw(union_ex diff_ex);
 
-use XXX;
 
 has 'print'     => (is => 'ro', required => 1);
 has 'fillers'   => (is => 'rw', default => sub { {} });
diff --git a/lib/Slic3r/Fill/Base.pm b/lib/Slic3r/Fill/Base.pm
index c8054e6b7..b104de3d5 100644
--- a/lib/Slic3r/Fill/Base.pm
+++ b/lib/Slic3r/Fill/Base.pm
@@ -1,7 +1,6 @@
 package Slic3r::Fill::Base;
 use Moo;
 
-use XXX;
 
 has 'print'               => (is => 'rw');
 has 'layer'               => (is => 'rw');
diff --git a/lib/Slic3r/Fill/Concentric.pm b/lib/Slic3r/Fill/Concentric.pm
index a5e4e1b38..5c97490d0 100644
--- a/lib/Slic3r/Fill/Concentric.pm
+++ b/lib/Slic3r/Fill/Concentric.pm
@@ -4,7 +4,6 @@ use Moo;
 extends 'Slic3r::Fill::Base';
 
 use Slic3r::Geometry qw(scale unscale X1 Y1 X2 Y2);
-use XXX;
 
 sub fill_surface {
     my $self = shift;
diff --git a/lib/Slic3r/Fill/Honeycomb.pm b/lib/Slic3r/Fill/Honeycomb.pm
index 4f2cda463..9d46e55bd 100644
--- a/lib/Slic3r/Fill/Honeycomb.pm
+++ b/lib/Slic3r/Fill/Honeycomb.pm
@@ -7,7 +7,6 @@ has 'cache' => (is => 'rw', default => sub {{}});
 
 use Slic3r::Geometry qw(PI X1 Y1 X2 Y2 X Y scale);
 use Slic3r::Geometry::Clipper qw(intersection_ex);
-use XXX;
 
 sub angles () { [0, PI/3, PI/3*2] }
 
diff --git a/lib/Slic3r/Fill/PlanePath.pm b/lib/Slic3r/Fill/PlanePath.pm
index c61b5b7d7..daeb13dea 100644
--- a/lib/Slic3r/Fill/PlanePath.pm
+++ b/lib/Slic3r/Fill/PlanePath.pm
@@ -4,7 +4,6 @@ use Moo;
 extends 'Slic3r::Fill::Base';
 
 use Slic3r::Geometry qw(scale bounding_box X1 Y1 X2 Y2);
-use XXX;
 
 sub multiplier () { 1 }
 
diff --git a/lib/Slic3r/Fill/Rectilinear.pm b/lib/Slic3r/Fill/Rectilinear.pm
index 8a546f795..904e6b5eb 100644
--- a/lib/Slic3r/Fill/Rectilinear.pm
+++ b/lib/Slic3r/Fill/Rectilinear.pm
@@ -4,7 +4,6 @@ use Moo;
 extends 'Slic3r::Fill::Base';
 
 use Slic3r::Geometry qw(X1 Y1 X2 Y2 A B X Y scale unscale epsilon);
-use XXX;
 
 sub fill_surface {
     my $self = shift;
diff --git a/lib/Slic3r/Fill/Rectilinear2.pm b/lib/Slic3r/Fill/Rectilinear2.pm
index d8b8f0bb0..7fb3ca679 100644
--- a/lib/Slic3r/Fill/Rectilinear2.pm
+++ b/lib/Slic3r/Fill/Rectilinear2.pm
@@ -4,7 +4,6 @@ use Moo;
 extends 'Slic3r::Fill::Base';
 
 use Slic3r::Geometry qw(scale X1 Y1 X2 Y2 A B X Y);
-use XXX;
 
 sub fill_surface {
     my $self = shift;
diff --git a/lib/Slic3r/Format/AMF.pm b/lib/Slic3r/Format/AMF.pm
index 901cb4544..247914484 100644
--- a/lib/Slic3r/Format/AMF.pm
+++ b/lib/Slic3r/Format/AMF.pm
@@ -2,7 +2,6 @@ package Slic3r::Format::AMF;
 use Moo;
 
 use Slic3r::Geometry qw(X Y Z);
-use XXX;
 
 sub read_file {
     my $self = shift;
diff --git a/lib/Slic3r/Format/AMF/Parser.pm b/lib/Slic3r/Format/AMF/Parser.pm
index 4d9394973..48f8521b8 100644
--- a/lib/Slic3r/Format/AMF/Parser.pm
+++ b/lib/Slic3r/Format/AMF/Parser.pm
@@ -3,7 +3,6 @@ use strict;
 use warnings;
 
 use XML::SAX::PurePerl;
-use XXX;
 
 use base 'XML::SAX::Base';
 
diff --git a/lib/Slic3r/Format/STL.pm b/lib/Slic3r/Format/STL.pm
index 91630a7b7..abdef000e 100644
--- a/lib/Slic3r/Format/STL.pm
+++ b/lib/Slic3r/Format/STL.pm
@@ -2,7 +2,6 @@ package Slic3r::Format::STL;
 use Moo;
 
 use Slic3r::Geometry qw(X Y Z triangle_normal);
-use XXX;
 
 sub read_file {
     my $self = shift;
diff --git a/lib/Slic3r/Geometry.pm b/lib/Slic3r/Geometry.pm
index a39bb305a..f2339e0ce 100644
--- a/lib/Slic3r/Geometry.pm
+++ b/lib/Slic3r/Geometry.pm
@@ -22,7 +22,6 @@ our @EXPORT_OK = qw(
     polyline_remove_short_segments normal triangle_normal polygon_is_convex
 );
 
-use XXX;
 
 use constant PI => 4 * atan2(1, 1);
 use constant A => 0;
diff --git a/lib/Slic3r/Layer.pm b/lib/Slic3r/Layer.pm
index e72cc57c9..5642ed8f1 100644
--- a/lib/Slic3r/Layer.pm
+++ b/lib/Slic3r/Layer.pm
@@ -4,7 +4,6 @@ use Moo;
 use Math::Clipper ':all';
 use Slic3r::Geometry qw(scale collinear X Y A B PI rad2deg_dir bounding_box_center);
 use Slic3r::Geometry::Clipper qw(union_ex diff_ex intersection_ex xor_ex is_counter_clockwise);
-use XXX;
 
 # a sequential number of layer, starting at 0
 has 'id' => (
diff --git a/lib/Slic3r/Perimeter.pm b/lib/Slic3r/Perimeter.pm
index a7150456a..a02b366d7 100644
--- a/lib/Slic3r/Perimeter.pm
+++ b/lib/Slic3r/Perimeter.pm
@@ -4,7 +4,6 @@ use Moo;
 use Math::Clipper ':all';
 use Slic3r::Geometry qw(X Y PI shortest_path scale unscale);
 use Slic3r::Geometry::Clipper qw(diff_ex);
-use XXX;
 
 sub make_perimeter {
     my $self = shift;
diff --git a/lib/Slic3r/Polyline.pm b/lib/Slic3r/Polyline.pm
index 5b8a09b8c..e7e886678 100644
--- a/lib/Slic3r/Polyline.pm
+++ b/lib/Slic3r/Polyline.pm
@@ -5,7 +5,6 @@ use warnings;
 use Math::Clipper qw();
 use Slic3r::Geometry qw(A B polyline_remove_parallel_continuous_edges polyline_remove_acute_vertices
     move_points same_point);
-use XXX;
 
 # the constructor accepts an array(ref) of points
 sub new {
diff --git a/lib/Slic3r/Print.pm b/lib/Slic3r/Print.pm
index 846c88c2d..488f327bc 100644
--- a/lib/Slic3r/Print.pm
+++ b/lib/Slic3r/Print.pm
@@ -6,7 +6,6 @@ use Math::ConvexHull 1.0.4 qw(convex_hull);
 use Slic3r::Geometry qw(X Y Z PI MIN MAX scale unscale move_points);
 use Slic3r::Geometry::Clipper qw(explode_expolygons safety_offset diff_ex intersection_ex
     union_ex offset JT_ROUND JT_MITER);
-use XXX;
 
 has 'x_length'          => (is => 'ro', required => 1);
 has 'y_length'          => (is => 'ro', required => 1);
diff --git a/lib/Slic3r/Skein.pm b/lib/Slic3r/Skein.pm
index 45cead013..d667422ed 100644
--- a/lib/Slic3r/Skein.pm
+++ b/lib/Slic3r/Skein.pm
@@ -5,7 +5,6 @@ use Config;
 use File::Basename qw(basename fileparse);
 use Slic3r::Geometry qw(PI unscale);
 use Time::HiRes qw(gettimeofday tv_interval);
-use XXX;
 
 # full path (relative or absolute) to the input file
 has 'input_file'    => (is => 'ro', required => 1);
diff --git a/lib/Slic3r/TriangleMesh.pm b/lib/Slic3r/TriangleMesh.pm
index 32f02cf5f..a3c21c371 100644
--- a/lib/Slic3r/TriangleMesh.pm
+++ b/lib/Slic3r/TriangleMesh.pm
@@ -2,7 +2,6 @@ package Slic3r::TriangleMesh;
 use Moo;
 
 use Slic3r::Geometry qw(X Y Z A B unscale same_point);
-use XXX;
 
 # public
 has 'vertices'      => (is => 'ro', required => 1);         # id => [ [$x1,$y1],[$x2,$y2],[$x3,$y3] ]
diff --git a/slic3r.pl b/slic3r.pl
index a3175221e..f07c613c9 100755
--- a/slic3r.pl
+++ b/slic3r.pl
@@ -10,7 +10,6 @@ BEGIN {
 
 use Getopt::Long qw(:config no_auto_abbrev);
 use Slic3r;
-use XXX;
 $|++;
 
 my %opt = ();
diff --git a/t/stl.t b/t/stl.t
index 02212dfcd..517e9e1ff 100644
--- a/t/stl.t
+++ b/t/stl.t
@@ -11,7 +11,6 @@ BEGIN {
 
 use Slic3r;
 use Slic3r::Geometry qw(X Y Z A B);
-use XXX;
 
 my @lines;
 my $z = 20;