diff --git a/src/libslic3r/GCode.cpp b/src/libslic3r/GCode.cpp
index aa857e8e4..02fefceec 100644
--- a/src/libslic3r/GCode.cpp
+++ b/src/libslic3r/GCode.cpp
@@ -442,6 +442,7 @@ std::vector<GCode::LayerToPrint> GCode::collect_layers_to_print(const PrintObjec
     // Pair the object layers with the support layers by z.
     size_t idx_object_layer  = 0;
     size_t idx_support_layer = 0;
+    const LayerToPrint* last_extrusion_layer = nullptr;
     while (idx_object_layer < object.layers().size() || idx_support_layer < object.support_layers().size()) {
         LayerToPrint layer_to_print;
         layer_to_print.object_layer  = (idx_object_layer < object.layers().size()) ? object.layers()[idx_object_layer ++] : nullptr;
@@ -456,17 +457,25 @@ std::vector<GCode::LayerToPrint> GCode::collect_layers_to_print(const PrintObjec
             }
         }
 
-        // Let's make sure that the last layer is not empty, so we don't build on top of it.
-        if (! layers_to_print.empty()
-         && ((layer_to_print.object_layer && layer_to_print.object_layer->has_extrusions())
-          || (layer_to_print.support_layer && layer_to_print.support_layer->has_extrusions()))
-         && (! layers_to_print.back().object_layer  || ! layers_to_print.back().object_layer->has_extrusions())
-         && (! layers_to_print.back().support_layer || ! layers_to_print.back().support_layer->has_extrusions()))
-            throw std::runtime_error(_(L("Empty layers detected, the output would not be printable.")) + "\n\n" +
-                                     _(L("Object name: ")) + object.model_object()->name + "\n" + _(L("Print z: ")) +
-                                     std::to_string(layers_to_print.back().print_z()));
-
         layers_to_print.emplace_back(layer_to_print);
+
+        // In case there are extrusions on this layer, check there is a layer to lay it on.
+        if ((layer_to_print.object_layer && layer_to_print.object_layer->has_extrusions())
+         || (layer_to_print.support_layer && layer_to_print.support_layer->has_extrusions())) {
+            double support_contact_z = (last_extrusion_layer && last_extrusion_layer->support_layer)
+                                       ? object.config().support_material_contact_distance
+                                       : 0.;
+            double maximal_print_z = (last_extrusion_layer ? last_extrusion_layer->print_z() : 0.)
+                                    + layer_to_print.layer()->height
+                                    + support_contact_z;
+
+            if (layer_to_print.print_z() > maximal_print_z + EPSILON)
+                throw std::runtime_error(_(L("Empty layers detected, the output would not be printable.")) + "\n\n" +
+                                         _(L("Object name: ")) + object.model_object()->name + "\n" + _(L("Print z: ")) +
+                                         std::to_string(layers_to_print.back().print_z()));
+            // Remember last layer with extrusions.
+            last_extrusion_layer = &layers_to_print.back();
+        }
     }
 
     return layers_to_print;
@@ -766,7 +775,7 @@ void GCode::_do_export(Print &print, FILE *file)
         mm3_per_mm.erase(std::remove_if(mm3_per_mm.begin(), mm3_per_mm.end(), [](double v) { return v < 0.000001; }), mm3_per_mm.end());
         if (! mm3_per_mm.empty()) {
             // In order to honor max_print_speed we need to find a target volumetric
-            // speed that we can use throughout the print. So we define this target 
+            // speed that we can use throughout the print. So we define this target 
             // volumetric speed as the volumetric speed produced by printing the 
             // smallest cross-section at the maximum speed: any larger cross-section
             // will need slower feedrates.
@@ -833,7 +842,7 @@ void GCode::_do_export(Print &print, FILE *file)
             _writeln(file, GCodeTimeEstimator::Silent_First_M73_Output_Placeholder_Tag);
     }
 
-    // Prepare the helper object for replacing placeholders in custom G-code and output filename.
+    // Prepare the helper object for replacing placeholders in custom G-code and output filename.
     m_placeholder_parser = print.placeholder_parser();
     m_placeholder_parser.update_timestamp();
     print.update_object_placeholders(m_placeholder_parser.config_writable(), ".gcode");
@@ -2617,7 +2626,7 @@ std::string GCode::_extrude(const ExtrusionPath &path, std::string description,
             EXTRUDER_CONFIG(filament_max_volumetric_speed) / path.mm3_per_mm
         );
     }
-    double F = speed * 60;  // convert mm/sec to mm/min
+    double F = speed * 60;  // convert mm/sec to mm/min
     
     // extrude arc or line
     if (m_enable_extrusion_role_markers)
diff --git a/src/slic3r/GUI/GLTexture.hpp b/src/slic3r/GUI/GLTexture.hpp
index c4063b93d..c8fd01f41 100644
--- a/src/slic3r/GUI/GLTexture.hpp
+++ b/src/slic3r/GUI/GLTexture.hpp
@@ -5,6 +5,7 @@
 #include <string>
 #include <vector>
 #include <thread>
+#include <atomic>
 
 class wxImage;