diff --git a/xs/src/libslic3r/Format/3mf.cpp b/xs/src/libslic3r/Format/3mf.cpp
index 0467962c3d..2c32db1a67 100644
--- a/xs/src/libslic3r/Format/3mf.cpp
+++ b/xs/src/libslic3r/Format/3mf.cpp
@@ -1271,6 +1271,7 @@ namespace Slic3r {
         if ((std::abs(sx - sy) > 0.00001) || (std::abs(sx - sz) > 0.00001))
             return;
 
+#if 0 // use quaternions
         // rotations (extracted using quaternion)
         double inv_sx = 1.0 / sx;
         double inv_sy = 1.0 / sy;
@@ -1331,6 +1332,25 @@ namespace Slic3r {
             if (angle_z < 0.0)
                 angle_z += 2.0 * PI;
         }
+#else // use eigen library
+        double inv_sx = 1.0 / sx;
+        double inv_sy = 1.0 / sy;
+        double inv_sz = 1.0 / sz;
+
+        Eigen::Matrix3d m3x3;
+        m3x3 << (double)matrix(0, 0) * inv_sx, (double)matrix(0, 1) * inv_sy, (double)matrix(0, 2) * inv_sz,
+                (double)matrix(1, 0) * inv_sx, (double)matrix(1, 1) * inv_sy, (double)matrix(1, 2) * inv_sz,
+                (double)matrix(2, 0) * inv_sx, (double)matrix(2, 1) * inv_sy, (double)matrix(2, 2) * inv_sz;
+
+        Eigen::AngleAxisd rotation;
+        rotation.fromRotationMatrix(m3x3);
+
+        // invalid rotation axis, we currently handle only rotations around Z axis
+        if ((rotation.angle() != 0.0) && (rotation.axis() != Eigen::Vector3d::UnitZ()) && (rotation.axis() != -Eigen::Vector3d::UnitZ()))
+            return;
+
+        double angle_z = (rotation.axis() == Eigen::Vector3d::UnitZ()) ? rotation.angle() : -rotation.angle();
+#endif 
 
         instance.offset.x = offset_x;
         instance.offset.y = offset_y;
diff --git a/xs/src/libslic3r/Format/AMF.cpp b/xs/src/libslic3r/Format/AMF.cpp
index 83b50ec9e6..2633637569 100644
--- a/xs/src/libslic3r/Format/AMF.cpp
+++ b/xs/src/libslic3r/Format/AMF.cpp
@@ -13,6 +13,9 @@
 
 #include <boost/filesystem/operations.hpp>
 #include <boost/algorithm/string.hpp>
+//############################################################################################################################################
+#include <boost/nowide/fstream.hpp>
+//############################################################################################################################################
 #include <miniz/miniz_zip.h>
 
 #if 0
@@ -666,10 +669,21 @@ bool load_amf_archive(const char *path, PresetBundle* bundle, Model *model)
 // If bundle is not a null pointer, updates it if the amf file/archive contains config data
 bool load_amf(const char *path, PresetBundle* bundle, Model *model)
 {
-    if (boost::iends_with(path, ".zip.amf"))
-        return load_amf_archive(path, bundle, model);
-    else if (boost::iends_with(path, ".amf") || boost::iends_with(path, ".amf.xml"))
+    if (boost::iends_with(path, ".amf.xml"))
+        // backward compatibility with older slic3r output
         return load_amf_file(path, bundle, model);
+    else if (boost::iends_with(path, ".amf"))
+    {
+        boost::nowide::ifstream file(path, boost::nowide::ifstream::binary);
+        if (!file.good())
+            return false;
+
+        std::string zip_mask(2, '\0');
+        file.read(const_cast<char*>(zip_mask.data()), 2);
+        file.close();
+
+        return (zip_mask == "PK") ? load_amf_archive(path, bundle, model) : load_amf_file(path, bundle, model);
+    }
     else
         return false;
 }