diff --git a/lib/Slic3r.pm b/lib/Slic3r.pm
index 964e03f8..5339579c 100644
--- a/lib/Slic3r.pm
+++ b/lib/Slic3r.pm
@@ -57,7 +57,8 @@ our $resolution             = 0.00000001;
 our $layer_height           = 0.4;
 our $first_layer_height_ratio = 1;
 our $infill_every_layers    = 1;
-our $thickness_ratio        = 1;
+our $extrusion_width_ratio  = undef;
+our $flow_speed_ratio       = 1.2;
 our $flow_width;
 
 # print options
diff --git a/lib/Slic3r/Config.pm b/lib/Slic3r/Config.pm
index 8c802d0e..ae297e07 100644
--- a/lib/Slic3r/Config.pm
+++ b/lib/Slic3r/Config.pm
@@ -68,6 +68,10 @@ our $Options = {
         label   => 'Layer height (mm)',
         type    => 'f',
     },
+    'extrusion_width_ratio' => {
+        label   => 'Extrusion width (ratio over layer height; leave empty to calculate automatically)',
+        type    => 'f',
+    },
     'first_layer_height_ratio' => {
         label   => 'First layer height ratio',
         type    => 'f',
@@ -276,15 +280,21 @@ sub validate {
     die "First layer height can't be greater than --nozzle-diameter\n"
         if ($Slic3r::layer_height * $Slic3r::first_layer_height_ratio) > $Slic3r::nozzle_diameter;
     $Slic3r::flow_width = ($Slic3r::nozzle_diameter**2) 
-        * $Slic3r::thickness_ratio * PI / (4 * $Slic3r::layer_height);
+        * $Slic3r::flow_speed_ratio * PI / (4 * $Slic3r::layer_height);
     
     my $max_flow_width = $Slic3r::layer_height + $Slic3r::nozzle_diameter;
     if ($Slic3r::flow_width > $max_flow_width) {
-        $Slic3r::thickness_ratio = $max_flow_width / $Slic3r::flow_width;
+        $Slic3r::flow_speed_ratio = $max_flow_width / $Slic3r::flow_width;
         $Slic3r::flow_width = $max_flow_width;
     }
+    if ($Slic3r::extrusion_width_ratio) {
+        my $flow_width = $Slic3r::layer_height * $Slic3r::extrusion_width_ratio;
+        $Slic3r::flow_speed_ratio = $flow_width / $Slic3r::flow_width;
+        $Slic3r::flow_width = $flow_width;
+    }
     
     Slic3r::debugf "Flow width = $Slic3r::flow_width\n";
+    Slic3r::debugf "Flow speed ratio = $Slic3r::flow_speed_ratio\n";
     
     # --perimeters
     die "Invalid value for --perimeters\n"
diff --git a/lib/Slic3r/Extruder.pm b/lib/Slic3r/Extruder.pm
index b1fc895b..c9cd5eae 100644
--- a/lib/Slic3r/Extruder.pm
+++ b/lib/Slic3r/Extruder.pm
@@ -101,7 +101,7 @@ sub extrude {
     # calculate extrusion length per distance unit
     my $e = $Slic3r::resolution
         * (($Slic3r::nozzle_diameter**2) / ($Slic3r::filament_diameter ** 2))
-        * $Slic3r::thickness_ratio 
+        * $Slic3r::flow_speed_ratio 
         * $self->flow_ratio
         * $Slic3r::filament_packing_density
         * $path->depth_layers;
diff --git a/lib/Slic3r/GUI/OptionsGroup.pm b/lib/Slic3r/GUI/OptionsGroup.pm
index 3f4f9a84..877aaae7 100644
--- a/lib/Slic3r/GUI/OptionsGroup.pm
+++ b/lib/Slic3r/GUI/OptionsGroup.pm
@@ -32,7 +32,7 @@ sub new {
                 $size = Wx::Size->new($opt->{width} || -1, $opt->{height} || -1);
             }
             
-            $field = Wx::TextCtrl->new($parent, -1, Slic3r::Config->get($opt_key),
+            $field = Wx::TextCtrl->new($parent, -1, Slic3r::Config->get($opt_key) || '',
                 Wx::wxDefaultPosition, $size, $style);
             EVT_TEXT($parent, $field, sub { Slic3r::Config->set($opt_key, $field->GetValue) });
             push @reload_callbacks, sub { $field->SetValue(Slic3r::Config->get($opt_key)) };
diff --git a/lib/Slic3r/GUI/SkeinPanel.pm b/lib/Slic3r/GUI/SkeinPanel.pm
index 55459642..f59d5031 100644
--- a/lib/Slic3r/GUI/SkeinPanel.pm
+++ b/lib/Slic3r/GUI/SkeinPanel.pm
@@ -51,6 +51,10 @@ sub new {
             title => 'Custom GCODE',
             options => [qw(start_gcode end_gcode)],
         },
+        extrusion => {
+            title => 'Extrusion',
+            options => [qw(extrusion_width_ratio)],
+        },
     );
     $self->{panels} = \%panels;
     
@@ -73,13 +77,17 @@ sub new {
         return $tab;
     };
     
-    my $tab1 = $make_tab->([qw(transform accuracy skirt)], [qw(print retract)]);
-    my $tab2 = $make_tab->([qw(printer filament)], [qw(speed)]);
-    my $tab3 = $make_tab->([qw(gcode)]);
+    my @tabs = (
+        $make_tab->([qw(transform accuracy skirt)], [qw(print retract)]),
+        $make_tab->([qw(printer filament)], [qw(speed)]),
+        $make_tab->([qw(gcode)]),
+        $make_tab->([qw(extrusion)]),
+    );
     
-    $tabpanel->AddPage($tab1, "Print Settings");
-    $tabpanel->AddPage($tab2, "Printer and Filament");
-    $tabpanel->AddPage($tab3, "Start/End GCODE");
+    $tabpanel->AddPage($tabs[0], "Print Settings");
+    $tabpanel->AddPage($tabs[1], "Printer and Filament");
+    $tabpanel->AddPage($tabs[2], "Start/End GCODE");
+    $tabpanel->AddPage($tabs[3], "Advanced");
         
     my $buttons_sizer;
     {
diff --git a/slic3r.pl b/slic3r.pl
index 0d9e311d..03f374f4 100755
--- a/slic3r.pl
+++ b/slic3r.pl
@@ -35,7 +35,7 @@ GetOptions(
     # filament options
     'filament-diameter=f'           => \$Slic3r::filament_diameter,
     'filament-packing-density=f'    => \$Slic3r::filament_packing_density,
-    'temperature=i'         => \$Slic3r::temperature,
+    'temperature=i'                 => \$Slic3r::temperature,
     
     # speed options
     'print-feed-rate=i'             => \$Slic3r::print_feed_rate,
@@ -44,9 +44,10 @@ GetOptions(
     'bottom-layer-speed-ratio=f'    => \$Slic3r::bottom_layer_speed_ratio,
     
     # accuracy options
-    'layer-height=f'        => \$Slic3r::layer_height,
-    'first-layer-height-ratio=f' => \$Slic3r::first_layer_height_ratio,
-    'infill-every-layers=i' => \$Slic3r::infill_every_layers,
+    'layer-height=f'                => \$Slic3r::layer_height,
+    'extrusion-width-ratio=f'       => \$Slic3r::extrusion_width_ratio,
+    'first-layer-height-ratio=f'    => \$Slic3r::first_layer_height_ratio,
+    'infill-every-layers=i'         => \$Slic3r::infill_every_layers,
     
     # print options
     'perimeters=i'          => \$Slic3r::perimeters,
@@ -165,6 +166,9 @@ Usage: slic3r.pl [ OPTIONS ] file.stl
                         layer with (> 0, default: $Slic3r::first_layer_height_ratio)
     --infill-every-layers
                         Infill every N layers (default: $Slic3r::infill_every_layers)
+    --extrusion-width-ratio
+                        Calculate the extrusion width as the layer height multiplied by
+                        this value (> 0, default: calculated automatically)
   
   Print options:
     --perimeters        Number of perimeters/horizontal skins (range: 1+,