diff --git a/xs/src/libslic3r/Format/OBJ.cpp b/xs/src/libslic3r/Format/OBJ.cpp
index b79587d88..ea6b5604c 100644
--- a/xs/src/libslic3r/Format/OBJ.cpp
+++ b/xs/src/libslic3r/Format/OBJ.cpp
@@ -26,38 +26,83 @@ bool load_obj(const char *path, Model *model, const char *object_name_in)
 
     // Count the faces and verify, that all faces are triangular.
     size_t num_faces = 0;
+	size_t num_quads = 0;
     for (size_t i = 0; i < data.vertices.size(); ) {
         size_t j = i;
         for (; j < data.vertices.size() && data.vertices[j].coordIdx != -1; ++ j) ;
         if (i == j)
             continue;
-        if (j - i != 3) {
-            // Non-triangular faces are not supported as of now.
+		size_t face_vertices = j - i;
+		if (face_vertices != 3 && face_vertices != 4) {
+            // Non-triangular and non-quad faces are not supported as of now.
             return false;
         }
-        num_faces ++;
-        i = j;
+		if (face_vertices == 4)
+			++ num_quads;
+		++ num_faces;
+        i = j + 1;
     }
 
     // Convert ObjData into STL.
     TriangleMesh mesh;
     stl_file &stl = mesh.stl;
     stl.stats.type = inmemory;
-    stl.stats.number_of_facets = num_faces;
-    stl.stats.original_num_facets = num_faces;
+    stl.stats.number_of_facets = int(num_faces + num_quads);
+    stl.stats.original_num_facets = int(num_faces + num_quads);
+    // stl_allocate clears all the allocated data to zero, all normals are set to zeros as well.
     stl_allocate(&stl);
     size_t i_face = 0;
     for (size_t i = 0; i < data.vertices.size(); ++ i) {
         if (data.vertices[i].coordIdx == -1)
             continue;
         stl_facet &facet = stl.facet_start[i_face ++];
+        size_t     num_normals = 0;
+        stl_normal normal = { 0.f };
         for (unsigned int v = 0; v < 3; ++ v) {
             const ObjParser::ObjVertex &vertex = data.vertices[i++];
             memcpy(&facet.vertex[v].x, &data.coordinates[vertex.coordIdx*4], 3 * sizeof(float));
-            if (vertex.normalIdx != -1)
-                memcpy(&facet.normal.x, &data.normals[vertex.normalIdx*3], 3 * sizeof(float));
+            if (vertex.normalIdx != -1) {
+                normal.x += data.normals[vertex.normalIdx*3];
+                normal.y += data.normals[vertex.normalIdx*3+1];
+                normal.z += data.normals[vertex.normalIdx*3+2];
+                ++ num_normals;
+            }
         }
-    }
+		if (data.vertices[i].coordIdx != -1) {
+			// This is a quad. Produce the other triangle.
+			stl_facet &facet2 = stl.facet_start[i_face++];
+            facet2.vertex[0] = facet.vertex[0];
+            facet2.vertex[1] = facet.vertex[2];
+			const ObjParser::ObjVertex &vertex = data.vertices[i++];
+			memcpy(&facet2.vertex[2].x, &data.coordinates[vertex.coordIdx * 4], 3 * sizeof(float));
+			if (vertex.normalIdx != -1) {
+                normal.x += data.normals[vertex.normalIdx*3];
+                normal.y += data.normals[vertex.normalIdx*3+1];
+                normal.z += data.normals[vertex.normalIdx*3+2];
+                ++ num_normals;
+            }
+            if (num_normals == 4) {
+                // Normalize an average normal of a quad.
+                float len = sqrt(facet.normal.x*facet.normal.x + facet.normal.y*facet.normal.y + facet.normal.z*facet.normal.z);
+                if (len > EPSILON) {
+                    normal.x /= len;
+                    normal.y /= len;
+                    normal.z /= len;
+                    facet.normal = normal;
+                    facet2.normal = normal;
+                }
+            }
+        } else if (num_normals == 3) {
+            // Normalize an average normal of a triangle.
+            float len = sqrt(facet.normal.x*facet.normal.x + facet.normal.y*facet.normal.y + facet.normal.z*facet.normal.z);
+            if (len > EPSILON) {
+                normal.x /= len;
+                normal.y /= len;
+                normal.z /= len;
+                facet.normal = normal;
+            }
+        }
+	}
     stl_get_size(&stl);
     mesh.repair();
     if (mesh.facets_count() == 0) {
diff --git a/xs/src/libslic3r/Format/objparser.cpp b/xs/src/libslic3r/Format/objparser.cpp
index 753fc462b..d8b86b703 100644
--- a/xs/src/libslic3r/Format/objparser.cpp
+++ b/xs/src/libslic3r/Format/objparser.cpp
@@ -346,8 +346,8 @@ bool objparse(const char *path, ObjData &data)
 	}
 	::fclose(pFile);
 
-	printf("vertices: %d\r\n", data.vertices.size() / 4);
-	printf("coords: %d\r\n", data.coordinates.size());
+	// printf("vertices: %d\r\n", data.vertices.size() / 4);
+	// printf("coords: %d\r\n", data.coordinates.size());
 	return true;
 }