diff --git a/src/slic3r.cpp b/src/slic3r.cpp
index 8899639b7..bf2fb2be7 100644
--- a/src/slic3r.cpp
+++ b/src/slic3r.cpp
@@ -138,11 +138,11 @@ main(int argc, char **argv)
             std::string outfile = cli_config.output.value;
             if (outfile.empty()) outfile = model.objects.front()->input_file;
             // Check if the file is already a 3mf.
-            if(outfile.substr(outfile.find_first_of('.'), outfile.length()) == ".3mf")
-                outfile = outfile.substr(0, outfile.find_first_of('.')) + "_2" + ".3mf";
+            if(outfile.substr(outfile.find_last_of('.'), outfile.length()) == ".3mf")
+                outfile = outfile.substr(0, outfile.find_last_of('.')) + "_2" + ".3mf";
             else
                 // Remove the previous extension and add .3mf extention.
-                outfile = outfile.substr(0, outfile.find_first_of('.')) + ".3mf";
+                outfile = outfile.substr(0, outfile.find_last_of('.')) + ".3mf";
             IO::TMF::write(model, outfile);
             boost::nowide::cout << "File file exported to " << outfile << std::endl;
         } else if (cli_config.cut_x > 0 || cli_config.cut_y > 0 || cli_config.cut > 0) {
@@ -162,14 +162,20 @@ main(int argc, char **argv)
                 
                 ModelObject &upper = *out.objects[0];
                 ModelObject &lower = *out.objects[1];
+
+                // Use the input name and trim off the extension.
+                std::string outfile = cli_config.output.value;
+                if (outfile.empty()) outfile = model.objects.front()->input_file;
+                outfile = outfile.substr(0, outfile.find_last_of('.'));
+                std::cerr << outfile << "\n";
             
                 if (upper.facets_count() > 0) {
                     TriangleMesh m = upper.mesh();
-                    IO::STL::write(m, upper.input_file + "_upper.stl");
+                    IO::STL::write(m, outfile + "_upper.stl");
                 }
                 if (lower.facets_count() > 0) {
                     TriangleMesh m = lower.mesh();
-                    IO::STL::write(m, lower.input_file + "_lower.stl");
+                    IO::STL::write(m, outfile + "_lower.stl");
                 }
             }
         } else if (cli_config.cut_grid.value.x > 0 && cli_config.cut_grid.value.y > 0) {