diff --git a/resources/icons/splashscreen-gcodepreview.jpg b/resources/icons/splashscreen-gcodepreview.jpg
index 3bae384935..481c4a6e12 100644
Binary files a/resources/icons/splashscreen-gcodepreview.jpg and b/resources/icons/splashscreen-gcodepreview.jpg differ
diff --git a/resources/icons/splashscreen.jpg b/resources/icons/splashscreen.jpg
index 754e245880..08236bcccc 100644
Binary files a/resources/icons/splashscreen.jpg and b/resources/icons/splashscreen.jpg differ
diff --git a/src/libslic3r/Config.cpp b/src/libslic3r/Config.cpp
index 6755a63781..5db1d8179b 100644
--- a/src/libslic3r/Config.cpp
+++ b/src/libslic3r/Config.cpp
@@ -471,8 +471,8 @@ bool ConfigBase::set_deserialize_nothrow(const t_config_option_key &opt_key_src,
 {
     t_config_option_key opt_key = opt_key_src;
     std::string         value   = value_src;
-    // Both opt_key and value may be modified by _handle_legacy().
-    // If the opt_key is no more valid in this version of Slic3r, opt_key is cleared by _handle_legacy().
+    // Both opt_key and value may be modified by handle_legacy().
+    // If the opt_key is no more valid in this version of Slic3r, opt_key is cleared by handle_legacy().
     this->handle_legacy(opt_key, value);
     if (opt_key.empty())
         // Ignore the option.
diff --git a/src/libslic3r/Flow.cpp b/src/libslic3r/Flow.cpp
index 1645bf683a..9f4730261e 100644
--- a/src/libslic3r/Flow.cpp
+++ b/src/libslic3r/Flow.cpp
@@ -89,18 +89,11 @@ double Flow::extrusion_width(const std::string& opt_key, const ConfigOptionFloat
 
 	if (opt->percent) {
 		auto opt_key_layer_height = first_layer ? "first_layer_height" : "layer_height";
-    	auto opt_layer_height = config.option(opt_key_layer_height);
+        auto opt_layer_height = config.option(opt_key_layer_height);
     	if (opt_layer_height == nullptr)
     		throw_on_missing_variable(opt_key, opt_key_layer_height);
-    	double layer_height = opt_layer_height->getFloat();
-    	if (first_layer && static_cast<const ConfigOptionFloatOrPercent*>(opt_layer_height)->percent) {
-    		// first_layer_height depends on layer_height.
-	    	opt_layer_height = config.option("layer_height");
-	    	if (opt_layer_height == nullptr)
-	    		throw_on_missing_variable(opt_key, "layer_height");
-	    	layer_height *= 0.01 * opt_layer_height->getFloat();
-    	}
-		return opt->get_abs_value(layer_height);
+        assert(! first_layer || ! static_cast<const ConfigOptionFloatOrPercent*>(opt_layer_height)->percent);
+		return opt->get_abs_value(opt_layer_height->getFloat());
 	}
 
 	if (opt->value == 0.) {
@@ -238,13 +231,14 @@ Flow support_material_flow(const PrintObject *object, float layer_height)
 
 Flow support_material_1st_layer_flow(const PrintObject *object, float layer_height)
 {
-    const auto &width = (object->print()->config().first_layer_extrusion_width.value > 0) ? object->print()->config().first_layer_extrusion_width : object->config().support_material_extrusion_width;
+    const PrintConfig &print_config = object->print()->config();
+    const auto &width = (print_config.first_layer_extrusion_width.value > 0) ? print_config.first_layer_extrusion_width : object->config().support_material_extrusion_width;
     return Flow::new_from_config_width(
         frSupportMaterial,
         // The width parameter accepted by new_from_config_width is of type ConfigOptionFloatOrPercent, the Flow class takes care of the percent to value substitution.
         (width.value > 0) ? width : object->config().extrusion_width,
-        float(object->print()->config().nozzle_diameter.get_at(object->config().support_material_extruder-1)),
-        (layer_height > 0.f) ? layer_height : float(object->config().first_layer_height.get_abs_value(object->config().layer_height.value)));
+        float(print_config.nozzle_diameter.get_at(object->config().support_material_extruder-1)),
+        (layer_height > 0.f) ? layer_height : float(print_config.first_layer_height.get_abs_value(object->config().layer_height.value)));
 }
 
 Flow support_material_interface_flow(const PrintObject *object, float layer_height)
diff --git a/src/libslic3r/Format/SL1.cpp b/src/libslic3r/Format/SL1.cpp
index 64cb8b8154..4038cb0467 100644
--- a/src/libslic3r/Format/SL1.cpp
+++ b/src/libslic3r/Format/SL1.cpp
@@ -248,7 +248,7 @@ std::vector<ExPolygons> extract_slices_from_sla_archive(
     {
         double          incr, val, prev;
         bool            stop = false;
-        tbb::spin_mutex mutex;
+        tbb::spin_mutex mutex = {};
     } st {100. / slices.size(), 0., 0.};
 
     tbb::parallel_for(size_t(0), arch.images.size(),
@@ -371,6 +371,13 @@ void fill_iniconf(ConfMap &m, const SLAPrint &print)
     m["numSlow"]      = std::to_string(stats.slow_layers_count);
     m["numFast"]      = std::to_string(stats.fast_layers_count);
     m["printTime"]    = std::to_string(stats.estimated_print_time);
+
+    bool hollow_en = false;
+    auto it = print.objects().begin();
+    while (!hollow_en && it != print.objects().end())
+        hollow_en = (*it++)->config().hollowing_enable;
+
+    m["hollow"] = hollow_en ? "1" : "0";
     
     m["action"] = "print";
 }
diff --git a/src/libslic3r/GCode.cpp b/src/libslic3r/GCode.cpp
index a799408109..c5b28b3a01 100644
--- a/src/libslic3r/GCode.cpp
+++ b/src/libslic3r/GCode.cpp
@@ -1111,7 +1111,8 @@ void GCode::_do_export(Print& print, FILE* file, ThumbnailsGeneratorCallback thu
     // Write some terse information on the slicing parameters.
     const PrintObject *first_object         = print.objects().front();
     const double       layer_height         = first_object->config().layer_height.value;
-    const double       first_layer_height   = first_object->config().first_layer_height.get_abs_value(layer_height);
+    assert(! print.config().first_layer_height.percent);
+    const double       first_layer_height   = print.config().first_layer_height.value;
     for (const PrintRegion* region : print.regions()) {
         _write_format(file, "; external perimeters extrusion width = %.2fmm\n", region->flow(*first_object, frExternalPerimeter, layer_height).width());
         _write_format(file, "; perimeters extrusion width = %.2fmm\n",          region->flow(*first_object, frPerimeter,         layer_height).width());
diff --git a/src/libslic3r/Preset.cpp b/src/libslic3r/Preset.cpp
index 7db61a20f1..c6a86b7193 100644
--- a/src/libslic3r/Preset.cpp
+++ b/src/libslic3r/Preset.cpp
@@ -296,6 +296,13 @@ void Preset::normalize(DynamicPrintConfig &config)
         if (auto *gap_fill_enabled = config.option<ConfigOptionBool>("gap_fill_enabled", false); gap_fill_enabled)
             gap_fill_enabled->value = false;
     }
+    if (auto *first_layer_height = config.option<ConfigOptionFloatOrPercent>("first_layer_height", false); first_layer_height && first_layer_height->percent)
+        if (const auto *layer_height = config.option<ConfigOptionFloat>("layer_height", false); layer_height) {
+            // Legacy conversion - first_layer_height moved from PrintObject setting to a Print setting, thus we are getting rid of the dependency
+            // of first_layer_height on PrintObject specific layer_height. Covert the first layer heigth to an absolute value.
+            first_layer_height->value   = first_layer_height->get_abs_value(layer_height->value);
+            first_layer_height->percent = false;
+        }
 }
 
 std::string Preset::remove_invalid_keys(DynamicPrintConfig &config, const DynamicPrintConfig &default_config)
diff --git a/src/libslic3r/Print.cpp b/src/libslic3r/Print.cpp
index ce5bf1b294..7fcb752978 100644
--- a/src/libslic3r/Print.cpp
+++ b/src/libslic3r/Print.cpp
@@ -1464,7 +1464,8 @@ std::string Print::validate(std::string* warning) const
             }
 
             // validate first_layer_height
-            double first_layer_height = object->config().get_abs_value("first_layer_height");
+            assert(! m_config.first_layer_height.percent);
+            double first_layer_height = m_config.first_layer_height.value;
             double first_layer_min_nozzle_diameter;
             if (object->has_raft()) {
                 // if we have raft layers, only support material extruder is used on first layer
@@ -1561,9 +1562,8 @@ BoundingBox Print::total_bounding_box() const
 
 double Print::skirt_first_layer_height() const
 {
-    if (m_objects.empty()) 
-        throw Slic3r::InvalidArgument("skirt_first_layer_height() can't be called without PrintObjects");
-    return m_objects.front()->config().get_abs_value("first_layer_height");
+    assert(! m_config.first_layer_height.percent);
+    return m_config.first_layer_height.value;
 }
 
 Flow Print::brim_flow() const
diff --git a/src/libslic3r/PrintConfig.cpp b/src/libslic3r/PrintConfig.cpp
index 5516b298d3..9f09bc9f34 100644
--- a/src/libslic3r/PrintConfig.cpp
+++ b/src/libslic3r/PrintConfig.cpp
@@ -995,10 +995,8 @@ void PrintConfigDef::init_fff_params()
     def->label = L("First layer height");
     def->category = L("Layers and Perimeters");
     def->tooltip = L("When printing with very low layer heights, you might still want to print a thicker "
-                   "bottom layer to improve adhesion and tolerance for non perfect build plates. "
-                   "This can be expressed as an absolute value or as a percentage (for example: 150%) "
-                   "over the default layer height.");
-    def->sidetext = L("mm or %");
+                   "bottom layer to improve adhesion and tolerance for non perfect build plates.");
+    def->sidetext = L("mm");
     def->ratio_over = "layer_height";
     def->set_default_value(new ConfigOptionFloatOrPercent(0.35, false));
 
@@ -3628,7 +3626,7 @@ std::string FullPrintConfig::validate()
         return "--layer-height must be a multiple of print resolution";
 
     // --first-layer-height
-    if (this->get_abs_value("first_layer_height") <= 0)
+    if (first_layer_height.value <= 0)
         return "Invalid value for --first-layer-height";
 
     // --filament-diameter
diff --git a/src/libslic3r/PrintConfig.hpp b/src/libslic3r/PrintConfig.hpp
index aab5096624..74cb5c7748 100644
--- a/src/libslic3r/PrintConfig.hpp
+++ b/src/libslic3r/PrintConfig.hpp
@@ -496,7 +496,6 @@ public:
     ConfigOptionBool                dont_support_bridges;
     ConfigOptionFloat               elefant_foot_compensation;
     ConfigOptionFloatOrPercent      extrusion_width;
-    ConfigOptionFloatOrPercent      first_layer_height;
     ConfigOptionBool                infill_only_where_needed;
     // Force the generation of solid shells between adjacent materials/volumes.
     ConfigOptionBool                interface_shells;
@@ -555,7 +554,6 @@ protected:
         OPT_PTR(dont_support_bridges);
         OPT_PTR(elefant_foot_compensation);
         OPT_PTR(extrusion_width);
-        OPT_PTR(first_layer_height);
         OPT_PTR(infill_only_where_needed);
         OPT_PTR(interface_shells);
         OPT_PTR(layer_height);
@@ -950,6 +948,7 @@ public:
     ConfigOptionFloat               first_layer_acceleration;
     ConfigOptionInts                first_layer_bed_temperature;
     ConfigOptionFloatOrPercent      first_layer_extrusion_width;
+    ConfigOptionFloatOrPercent      first_layer_height;
     ConfigOptionFloatOrPercent      first_layer_speed;
     ConfigOptionInts                first_layer_temperature;
     ConfigOptionInts                full_fan_speed_layer;
@@ -1025,6 +1024,7 @@ protected:
         OPT_PTR(first_layer_acceleration);
         OPT_PTR(first_layer_bed_temperature);
         OPT_PTR(first_layer_extrusion_width);
+        OPT_PTR(first_layer_height);
         OPT_PTR(first_layer_speed);
         OPT_PTR(first_layer_temperature);
         OPT_PTR(full_fan_speed_layer);
diff --git a/src/libslic3r/Slicing.cpp b/src/libslic3r/Slicing.cpp
index d0b1e9ce26..82b3cf1b66 100644
--- a/src/libslic3r/Slicing.cpp
+++ b/src/libslic3r/Slicing.cpp
@@ -64,9 +64,9 @@ SlicingParameters SlicingParameters::create_from_config(
 	coordf_t				 object_height,
 	const std::vector<unsigned int> &object_extruders)
 {
-    coordf_t first_layer_height                      = (object_config.first_layer_height.value <= 0) ? 
-        object_config.layer_height.value : 
-        object_config.first_layer_height.get_abs_value(object_config.layer_height.value);
+    assert(! print_config.first_layer_height.percent);
+    coordf_t first_layer_height                      = (print_config.first_layer_height.value <= 0) ? 
+        object_config.layer_height.value : print_config.first_layer_height.value;
     // If object_config.support_material_extruder == 0 resp. object_config.support_material_interface_extruder == 0,
     // print_config.nozzle_diameter.get_at(size_t(-1)) returns the 0th nozzle diameter,
     // which is consistent with the requirement that if support_material_extruder == 0 resp. support_material_interface_extruder == 0,
diff --git a/src/slic3r/GUI/ConfigManipulation.cpp b/src/slic3r/GUI/ConfigManipulation.cpp
index cd7805a880..d557585384 100644
--- a/src/slic3r/GUI/ConfigManipulation.cpp
+++ b/src/slic3r/GUI/ConfigManipulation.cpp
@@ -45,7 +45,7 @@ void ConfigManipulation::update_print_fff_config(DynamicPrintConfig* config, con
     // layer_height shouldn't be equal to zero
     if (config->opt_float("layer_height") < EPSILON)
     {
-        const wxString msg_text = _(L("Zero layer height is not valid.\n\nThe layer height will be reset to 0.01."));
+        const wxString msg_text = _(L("Layer height is not valid.\n\nThe layer height will be reset to 0.01."));
         wxMessageDialog dialog(nullptr, msg_text, _(L("Layer height")), wxICON_WARNING | wxOK);
         DynamicPrintConfig new_conf = *config;
         is_msg_dlg_already_exist = true;
@@ -55,9 +55,9 @@ void ConfigManipulation::update_print_fff_config(DynamicPrintConfig* config, con
         is_msg_dlg_already_exist = false;
     }
 
-    if (fabs(config->option<ConfigOptionFloatOrPercent>("first_layer_height")->value - 0) < EPSILON)
+    if (config->option<ConfigOptionFloatOrPercent>("first_layer_height")->value < EPSILON)
     {
-        const wxString msg_text = _(L("Zero first layer height is not valid.\n\nThe first layer height will be reset to 0.01."));
+        const wxString msg_text = _(L("First layer height is not valid.\n\nThe first layer height will be reset to 0.01."));
         wxMessageDialog dialog(nullptr, msg_text, _(L("First layer height")), wxICON_WARNING | wxOK);
         DynamicPrintConfig new_conf = *config;
         is_msg_dlg_already_exist = true;
diff --git a/src/slic3r/GUI/GUI_App.cpp b/src/slic3r/GUI/GUI_App.cpp
index 3023041f6d..f18a1fbe4e 100644
--- a/src/slic3r/GUI/GUI_App.cpp
+++ b/src/slic3r/GUI/GUI_App.cpp
@@ -244,10 +244,11 @@ private:
 
             // credits infornation
             credits =   title + " " +
-                        _L("is based on Slic3r by Alessandro Ranellucci and the RepRap community.") + "\n\n" +
+                        _L("is based on Slic3r by Alessandro Ranellucci and the RepRap community.") + "\n" +
+                        _L("Developed by Prusa Research.")+ "\n\n" +
                         title + " " + _L("is licensed under the") + " " + _L("GNU Affero General Public License, version 3") + "\n\n" +
                         _L("Contributions by Vojtech Bubnik, Enrico Turri, Oleksandra Iushchenko, Tamas Meszaros, Lukas Matena, Vojtech Kral, David Kocik and numerous others.") + "\n\n" +
-                        _L("Artwork model by Nora Al-Badri and Jan Nikolai Nelles");
+                        _L("Artwork model by M Boyer");
 
             title_font = version_font = credits_font = init_font;
         }
diff --git a/src/slic3r/GUI/PresetHints.cpp b/src/slic3r/GUI/PresetHints.cpp
index 181dcfda47..0e2b7f8364 100644
--- a/src/slic3r/GUI/PresetHints.cpp
+++ b/src/slic3r/GUI/PresetHints.cpp
@@ -86,7 +86,8 @@ std::string PresetHints::maximum_volumetric_flow_description(const PresetBundle
 
     // Print config values
     double layer_height                     = print_config.opt_float("layer_height");
-    double first_layer_height               = print_config.get_abs_value("first_layer_height", layer_height);
+    assert(! print_config.option<ConfigOptionFloatOrPercent>("first_layer_height")->percent);
+    double first_layer_height               = print_config.opt_float("first_layer_height");
     double support_material_speed           = print_config.opt_float("support_material_speed");
     double support_material_interface_speed = print_config.get_abs_value("support_material_interface_speed", support_material_speed);
     double bridge_speed                     = print_config.opt_float("bridge_speed");
diff --git a/t/flow.t b/t/flow.t
index 4d7ee5ca2a..50c4916049 100644
--- a/t/flow.t
+++ b/t/flow.t
@@ -21,7 +21,7 @@ use Slic3r::Test;
     $config->set('fill_density', 0.4);
     $config->set('bottom_solid_layers', 1);
     $config->set('first_layer_extrusion_width', 2);
-    $config->set('first_layer_height', '100%');
+    $config->set('first_layer_height', $config->layer_height);
     $config->set('filament_diameter', [ 3.0 ]);
     $config->set('nozzle_diameter', [ 0.5 ]);
     
diff --git a/t/layers.t b/t/layers.t
index a9f7dfe39f..4d958808a6 100644
--- a/t/layers.t
+++ b/t/layers.t
@@ -49,7 +49,7 @@ use Slic3r::Test qw(_eq);
     $config->set('first_layer_height', 0.2);
     ok $test->(), "absolute first layer height";
 
-    $config->set('first_layer_height', '60%');
+    $config->set('first_layer_height', 0.6 * $config->layer_height);
     ok $test->(), "relative first layer height";
 
     $config->set('z_offset', 0.9);
diff --git a/t/multi.t b/t/multi.t
index 8e7225bec7..e74a7a1a8b 100644
--- a/t/multi.t
+++ b/t/multi.t
@@ -181,7 +181,7 @@ use Slic3r::Test;
     my $config = Slic3r::Config::new_from_defaults;
     $config->set('nozzle_diameter', [0.6,0.6,0.6,0.6]);
     $config->set('layer_height', 0.4);
-    $config->set('first_layer_height', '100%');
+    $config->set('first_layer_height', $config->layer_height);
     $config->set('skirts', 0);
     my $print = Slic3r::Test::init_print($model, config => $config);
     
diff --git a/t/shells.t b/t/shells.t
index 47b5c8881d..29bc0b5f00 100644
--- a/t/shells.t
+++ b/t/shells.t
@@ -84,7 +84,7 @@ use Slic3r::Test;
 {
     my $config = Slic3r::Config::new_from_defaults;
     $config->set('layer_height', 0.3);
-    $config->set('first_layer_height', '100%');
+    $config->set('first_layer_height', $config->layer_height);
     $config->set('bottom_solid_layers', 0);
     $config->set('top_solid_layers', 3);
     $config->set('cooling', [ 0 ]);
@@ -119,7 +119,7 @@ use Slic3r::Test;
     $config->set('cooling', [ 0 ]);             # prevent speed alteration
     $config->set('first_layer_speed', '100%');  # prevent speed alteration
     $config->set('layer_height', 0.4);
-    $config->set('first_layer_height', '100%');
+    $config->set('first_layer_height', $config->layer_height);
     $config->set('extrusion_width', 0.55);
     $config->set('bottom_solid_layers', 3);
     $config->set('top_solid_layers', 0);
@@ -142,7 +142,7 @@ use Slic3r::Test;
     $config->set('cooling', [ 0 ]);             # prevent speed alteration
     $config->set('first_layer_speed', '100%');  # prevent speed alteration
     $config->set('layer_height', 0.4);
-    $config->set('first_layer_height', '100%');
+    $config->set('first_layer_height', $config->layer_height);
     $config->set('bottom_solid_layers', 3);
     $config->set('top_solid_layers', 3);
     $config->set('solid_infill_speed', 99);
@@ -170,7 +170,7 @@ use Slic3r::Test;
     $config->set('spiral_vase', 1);
     $config->set('bottom_solid_layers', 0);
     $config->set('skirts', 0);
-    $config->set('first_layer_height', '100%');
+    $config->set('first_layer_height', $config->layer_height);
     $config->set('start_gcode', '');
     $config->set('temperature', [200]);
     $config->set('first_layer_temperature', [205]);
@@ -231,8 +231,8 @@ use Slic3r::Test;
     $config->set('bottom_solid_layers', 0);
     $config->set('retract_layer_change', [0]);
     $config->set('skirts', 0);
-    $config->set('first_layer_height', '100%');
     $config->set('layer_height', 0.4);
+    $config->set('first_layer_height', $config->layer_height);
     $config->set('start_gcode', '');
 #    $config->set('use_relative_e_distances', 1);
     $config->validate;
@@ -310,7 +310,7 @@ use Slic3r::Test;
 #    $config->set('spiral_vase', 1);
 #    $config->set('bottom_solid_layers', 0);
 #    $config->set('skirts', 0);
-#    $config->set('first_layer_height', '100%');
+#    $config->set('first_layer_height', $config->layer_height);
 #    $config->set('start_gcode', '');
 #    
 #    my $print = Slic3r::Test::init_print('two_hollow_squares', config => $config);
diff --git a/t/thin.t b/t/thin.t
index 9147236ee5..50e7abc950 100644
--- a/t/thin.t
+++ b/t/thin.t
@@ -18,7 +18,7 @@ use Slic3r::Test;
 if (0) {
     my $config = Slic3r::Config::new_from_defaults;
     $config->set('layer_height', 0.2);
-    $config->set('first_layer_height', '100%');
+    $config->set('first_layer_height', $config->layer_height);
     $config->set('extrusion_width', 0.5);
     $config->set('first_layer_extrusion_width', '200%'); # check this one too
     $config->set('skirts', 0);
diff --git a/tests/fff_print/test_flow.cpp b/tests/fff_print/test_flow.cpp
index 08ba15a84a..dc73f4b6ec 100644
--- a/tests/fff_print/test_flow.cpp
+++ b/tests/fff_print/test_flow.cpp
@@ -24,7 +24,7 @@ SCENARIO("Extrusion width specifics", "[Flow]") {
 			{ "skirts",				1 },
 			{ "perimeters",			3 },
 			{ "fill_density",		"40%" },
-			{ "first_layer_height", "100%" }
+			{ "first_layer_height", 0.3 }
 			});
 
         WHEN("first layer width set to 2mm") {
diff --git a/tests/fff_print/test_support_material.cpp b/tests/fff_print/test_support_material.cpp
index 1b85532d31..442db7654f 100644
--- a/tests/fff_print/test_support_material.cpp
+++ b/tests/fff_print/test_support_material.cpp
@@ -29,7 +29,7 @@ SCENARIO("SupportMaterial: support_layers_z and contact_distance", "[SupportMate
 	{
         ConstSupportLayerPtrsAdaptor support_layers = print.objects().front()->support_layers();
 
-		first_support_layer_height_ok = support_layers.front()->print_z == print.default_object_config().first_layer_height.value;
+		first_support_layer_height_ok = support_layers.front()->print_z == print.config().first_layer_height.value;
 
 		layer_height_minimum_ok = true;
 		layer_height_maximum_ok = true;
diff --git a/tests/libslic3r/test_placeholder_parser.cpp b/tests/libslic3r/test_placeholder_parser.cpp
index e632dc7057..8c56afc6d0 100644
--- a/tests/libslic3r/test_placeholder_parser.cpp
+++ b/tests/libslic3r/test_placeholder_parser.cpp
@@ -14,9 +14,12 @@ SCENARIO("Placeholder parser scripting", "[PlaceholderParser]") {
 	    { "nozzle_diameter", "0.6;0.6;0.6;0.6" },
 	    { "temperature", "357;359;363;378" }
 	});
-    // To test the "first_layer_extrusion_width" over "first_layer_heigth" over "layer_height" chain.
-    config.option<ConfigOptionFloatOrPercent>("first_layer_height")->value = 150.;
-    config.option<ConfigOptionFloatOrPercent>("first_layer_height")->percent = true;
+    // To test the "first_layer_extrusion_width" over "first_layer_heigth".
+    // "first_layer_heigth" over "layer_height" is no more supported after first_layer_height was moved from PrintObjectConfig to PrintConfig.
+//  config.option<ConfigOptionFloatOrPercent>("first_layer_height")->value = 150.;
+//  config.option<ConfigOptionFloatOrPercent>("first_layer_height")->percent = true;
+    config.option<ConfigOptionFloatOrPercent>("first_layer_height")->value = 1.5 * config.opt_float("layer_height");
+    config.option<ConfigOptionFloatOrPercent>("first_layer_height")->percent = false;
     // To let the PlaceholderParser throw when referencing first_layer_speed if it is set to percent, as the PlaceholderParser does not know
     // a percent to what.
     config.option<ConfigOptionFloatOrPercent>("first_layer_speed")->value = 50.;
@@ -50,7 +53,7 @@ SCENARIO("Placeholder parser scripting", "[PlaceholderParser]") {
     SECTION("math: int(-13.4)") { REQUIRE(parser.process("{int(-13.4)}") == "-13"); }
 
     // Test the "coFloatOrPercent" and "xxx_extrusion_width" substitutions.
-    // first_layer_extrusion_width ratio_over first_layer_heigth ratio_over layer_height
+    // first_layer_extrusion_width ratio_over first_layer_heigth.
     SECTION("perimeter_extrusion_width") { REQUIRE(std::stod(parser.process("{perimeter_extrusion_width}")) == Approx(0.67500001192092896)); }
     SECTION("first_layer_extrusion_width") { REQUIRE(std::stod(parser.process("{first_layer_extrusion_width}")) == Approx(0.9)); }
     SECTION("support_material_xy_spacing") { REQUIRE(std::stod(parser.process("{support_material_xy_spacing}")) == Approx(0.3375)); }
diff --git a/xs/t/15_config.t b/xs/t/15_config.t
index 55b6791015..4d032019c2 100644
--- a/xs/t/15_config.t
+++ b/xs/t/15_config.t
@@ -4,7 +4,7 @@ use strict;
 use warnings;
 
 use Slic3r::XS;
-use Test::More tests => 147;
+use Test::More tests => 143;
 
 foreach my $config (Slic3r::Config->new, Slic3r::Config::Static::new_FullPrintConfig) {
     $config->set('layer_height', 0.3);
@@ -70,10 +70,11 @@ foreach my $config (Slic3r::Config->new, Slic3r::Config::Static::new_FullPrintCo
     ok abs($config->get('first_layer_height') - 0.3) < 1e-4, 'set/get absolute floatOrPercent';
     is $config->opt_serialize('first_layer_height'), '0.3', 'serialize absolute floatOrPercent';
     
-    $config->set('first_layer_height', '50%');
-    $config->get_abs_value('first_layer_height');
-    ok abs($config->get_abs_value('first_layer_height') - 0.15) < 1e-4, 'set/get relative floatOrPercent';
-    is $config->opt_serialize('first_layer_height'), '50%', 'serialize relative floatOrPercent';
+# This is no more supported after first_layer_height was moved from PrintObjectConfig to PrintConfig.
+#    $config->set('first_layer_height', $config->get('layer_height'));
+#    $config->get_abs_value('first_layer_height');
+#    ok abs($config->get_abs_value('first_layer_height') - 0.15) < 1e-4, 'set/get relative floatOrPercent';
+#    is $config->opt_serialize('first_layer_height'), '50%', 'serialize relative floatOrPercent';
     
     # Uh-oh, we have no point option to test at the moment
     #ok $config->set('print_center', [50,80]), 'valid point coordinates';