diff --git a/xs/src/libslic3r/IO/AMF.cpp b/xs/src/libslic3r/IO/AMF.cpp
index ce49640d0..f0bb7a60a 100644
--- a/xs/src/libslic3r/IO/AMF.cpp
+++ b/xs/src/libslic3r/IO/AMF.cpp
@@ -1,4 +1,6 @@
 #include "../IO.hpp"
+#include <iostream>
+#include <fstream>
 #include <string.h>
 #include <map>
 #include <string>
@@ -495,109 +497,121 @@ AMF::read(std::string input_file, Model* model)
 bool
 AMF::write(Model& model, std::string output_file)
 {
-    FILE *file = ::fopen(output_file.c_str(), "wb");
-    if (file == NULL)
-        return false;
-
-    fprintf(file, "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n");
-    fprintf(file, "<amf unit=\"millimeter\">\n");
-    fprintf(file, "<metadata type=\"cad\">Slic3r %s</metadata>\n", SLIC3R_VERSION);
+    using namespace std;
+    
+    ofstream file;
+    file.open(output_file, ios::out | ios::trunc);
+    
+    file << "<?xml version=\"1.0\" encoding=\"UTF-8\"?>" << endl
+         << "<amf unit=\"millimeter\">" << endl
+         << "<metadata type=\"cad\">Slic3r " << SLIC3R_VERSION << "</metadata>" << endl;
+    
     for (const auto &material : model.materials) {
         if (material.first.empty())
             continue;
         // note that material-id must never be 0 since it's reserved by the AMF spec
-        fprintf(file, "  <material id=\"%s\">\n", material.first.c_str());
+        file << "  <material id=\"" << material.first << "\">" << endl;
         for (const auto &attr : material.second->attributes)
-             fprintf(file, "    <metadata type=\"%s\">%s</metadata>\n", attr.first.c_str(), attr.second.c_str());
+             file << "    <metadata type=\"" << attr.first << "\">" << attr.second << "</metadata>" << endl;
         for (const std::string &key : material.second->config.keys())
-             fprintf(file, "    <metadata type=\"slic3r.%s\">%s</metadata>\n", key.c_str(), material.second->config.serialize(key).c_str());
-        fprintf(file, "  </material>\n");
+             file << "    <metadata type=\"slic3r." << key << "\">"
+                  << material.second->config.serialize(key) << "</metadata>" << endl;
+        file << "  </material>" << endl;
     }
-    std::string instances;
-    for (size_t object_id = 0; object_id < model.objects.size(); ++ object_id) {
+    
+    ostringstream instances;
+    for (size_t object_id = 0; object_id < model.objects.size(); ++object_id) {
         ModelObject *object = model.objects[object_id];
-        fprintf(file, "  <object id=\"%zu\">\n", object_id);
+        file << "  <object id=\"" << object_id << "\">" << endl;
+        
         for (const std::string &key : object->config.keys())
-             fprintf(file, "    <metadata type=\"slic3r.%s\">%s</metadata>\n", key.c_str(), object->config.serialize(key).c_str());
-        if (! object->name.empty())
-            fprintf(file, "    <metadata type=\"name\">%s</metadata>\n", object->name.c_str());
+            file << "    <metadata type=\"slic3r." << key << "\">"
+                 << object->config.serialize(key) << "</metadata>" << endl;
+        
+        if (!object->name.empty())
+            file << "    <metadata type=\"name\">" << object->name << "</metadata>" << endl;
 
-        //FIXME Store the layer height ranges (ModelObject::layer_height_ranges)
-        fprintf(file, "    <mesh>\n");
-        fprintf(file, "      <vertices>\n");
-        std::vector<int> vertices_offsets;
-        int              num_vertices = 0;
+        //FIXME: Store the layer height ranges (ModelObject::layer_height_ranges)
+        file << "    <mesh>" << endl;
+        file << "      <vertices>" << endl;
+        
+        std::vector<size_t> vertices_offsets;
+        size_t num_vertices = 0;
+        
         for (ModelVolume *volume : object->volumes) {
-            volume->mesh.check_topology();
+            volume->mesh.require_shared_vertices();
             vertices_offsets.push_back(num_vertices);
-            auto &stl = volume->mesh.stl;
-            if (stl.v_shared == NULL)
-                stl_generate_shared_vertices(&stl);
-            for (size_t i = 0; i < stl.stats.shared_vertices; ++ i) {
+            const auto &stl = volume->mesh.stl;
+            for (size_t i = 0; i < stl.stats.shared_vertices; ++i)
                 // Subtract origin_translation in order to restore the coordinates of the parts
                 // before they were imported. Otherwise, when this AMF file is reimported parts
                 // will be placed in the plater correctly, but we will have lost origin_translation
                 // thus any additional part added will not align with the others.
                 // In order to do this we compensate for this translation in the instance placement
                 // below.
-                fprintf(file, "         <vertex>\n");
-                fprintf(file, "           <coordinates>\n");
-                fprintf(file, "             <x>%f</x>\n", stl.v_shared[i].x - object->origin_translation.x);
-                fprintf(file, "             <y>%f</y>\n", stl.v_shared[i].y - object->origin_translation.y);
-                fprintf(file, "             <z>%f</z>\n", stl.v_shared[i].z - object->origin_translation.z);
-                fprintf(file, "           </coordinates>\n");
-                fprintf(file, "         </vertex>\n");
-            }
+                file << "         <vertex>" << endl
+                     << "           <coordinates>" << endl
+                     << "             <x>" << (stl.v_shared[i].x - object->origin_translation.x) << "</x>" << endl
+                     << "             <y>" << (stl.v_shared[i].y - object->origin_translation.y) << "</y>" << endl
+                     << "             <z>" << (stl.v_shared[i].z - object->origin_translation.z) << "</z>" << endl
+                     << "           </coordinates>" << endl
+                     << "         </vertex>" << endl;
+            
             num_vertices += stl.stats.shared_vertices;
         }
-        fprintf(file, "      </vertices>\n");
-        for (size_t i_volume = 0; i_volume < object->volumes.size(); ++ i_volume) {
+        file << "      </vertices>" << endl;
+        
+        for (size_t i_volume = 0; i_volume < object->volumes.size(); ++i_volume) {
             ModelVolume *volume = object->volumes[i_volume];
             int vertices_offset = vertices_offsets[i_volume];
+            
             if (volume->material_id().empty())
-                fprintf(file, "      <volume>\n");
+                file << "      <volume>" << endl;
             else
-                fprintf(file, "      <volume materialid=\"%s\">\n", volume->material_id().c_str());
+                file << "      <volume materialid=\"" << volume->material_id() << "\">" << endl;
+            
             for (const std::string &key : volume->config.keys())
-                fprintf(file, "        <metadata type=\"slic3r.%s\">%s</metadata>\n", key.c_str(), volume->config.serialize(key).c_str());
-            if (! volume->name.empty())
-                fprintf(file, "        <metadata type=\"name\">%s</metadata>\n", volume->name.c_str());
+                file << "        <metadata type=\"slic3r." << key << "\">"
+                     << volume->config.serialize(key) << "</metadata>" << endl;
+            
+            if (!volume->name.empty())
+                file << "        <metadata type=\"name\">" << volume->name << "</metadata>" << endl;
+            
             if (volume->modifier)
-                fprintf(file, "        <metadata type=\"slic3r.modifier\">1</metadata>\n");
-            for (int i = 0; i < volume->mesh.stl.stats.number_of_facets; ++ i) {
-                fprintf(file, "        <triangle>\n");
+                file << "        <metadata type=\"slic3r.modifier\">1</metadata>" << endl;
+            
+            for (int i = 0; i < volume->mesh.stl.stats.number_of_facets; ++i) {
+                file << "        <triangle>" << endl;
                 for (int j = 0; j < 3; ++ j)
-                    fprintf(file, "          <v%d>%d</v%d>\n", j+1, volume->mesh.stl.v_indices[i].vertex[j] + vertices_offset, j+1);
-                fprintf(file, "        </triangle>\n");
+                    file << "          <v" << (j+1) << ">"
+                         << (volume->mesh.stl.v_indices[i].vertex[j] + vertices_offset)
+                         << "</v" << (j+1) << ">" << endl;
+                file << "        </triangle>" << endl;
             }
-            fprintf(file, "      </volume>\n");
-        }
-        fprintf(file, "    </mesh>\n");
-        fprintf(file, "  </object>\n");
-        for (const ModelInstance* instance : object->instances) {
-            char buf[512];
-            sprintf(buf,
-                "    <instance objectid=\"%zu\">\n"
-                "      <deltax>%lf</deltax>\n"
-                "      <deltay>%lf</deltay>\n"
-                "      <rz>%lf</rz>\n"
-                "      <scale>%lf</scale>\n"
-                "    </instance>\n",
-                object_id,
-                instance->offset.x + object->origin_translation.x,
-                instance->offset.y + object->origin_translation.y,
-                instance->rotation,
-                instance->scaling_factor);
-            instances.append(buf);
+            file << "      </volume>" << endl;
         }
+        file << "    </mesh>" << endl;
+        file << "  </object>" << endl;
+        
+        for (const ModelInstance* instance : object->instances)
+            instances
+                << "    <instance objectid=\"" << object_id << "\">" << endl
+                << "      <deltax>" << instance->offset.x + object->origin_translation.x << "</deltax>" << endl
+                << "      <deltay>" << instance->offset.y + object->origin_translation.y << "</deltay>" << endl
+                << "      <rz>%" << instance->rotation << "</rz>" << endl
+                << "      <scale>" << instance->scaling_factor << "</scale>" << endl
+                << "    </instance>" << endl;
     }
-    if (! instances.empty()) {
-        fprintf(file, "  <constellation id=\"1\">\n");
-        fwrite(instances.data(), instances.size(), 1, file);
-        fprintf(file, "  </constellation>\n");
-    }
-    fprintf(file, "</amf>\n");
-    fclose(file);
+    
+    std::string instances_str = instances.str();
+    if (!instances_str.empty())
+        file << "  <constellation id=\"1\">" << endl
+             << instances_str
+             << "  </constellation>" << endl;
+    
+    file << "</amf>" << endl;
+    
+    file.close();
     return true;
 }
 
diff --git a/xs/src/libslic3r/TriangleMesh.hpp b/xs/src/libslic3r/TriangleMesh.hpp
index cba8ba43e..51a4e9df4 100644
--- a/xs/src/libslic3r/TriangleMesh.hpp
+++ b/xs/src/libslic3r/TriangleMesh.hpp
@@ -58,6 +58,7 @@ class TriangleMesh
     bool needed_repair() const;
     size_t facets_count() const;
     void extrude_tin(float offset);
+    void require_shared_vertices();
     
     static TriangleMesh make_cube(double x, double y, double z);
     static TriangleMesh make_cylinder(double r, double h, double fa=(2*PI/360));
@@ -67,7 +68,6 @@ class TriangleMesh
     bool repaired;
     
     private:
-    void require_shared_vertices();
     friend class TriangleMeshSlicer<X>;
     friend class TriangleMeshSlicer<Y>;
     friend class TriangleMeshSlicer<Z>;