diff --git a/extras/win32-portable/openslides.c b/extras/win32-portable/openslides.c
index 7e6abdcc4..e69d9824b 100644
--- a/extras/win32-portable/openslides.c
+++ b/extras/win32-portable/openslides.c
@@ -12,6 +12,17 @@
 
 #include <Python.h>
 
+#define PYTHON_DLL_PATH "\\Dlls\\python27.dll"
+
+static void (*py_initialize)(void) = 0;
+static void (*py_finalize)(void) = 0;
+static void (*py_set_program_name)(char *) = 0;
+static void (*py_set_python_home)(char *) = 0;
+static int (*py_run_simple_string_flags)(const char *, PyCompilerFlags *) = 0;
+static void (*py_sys_set_argv_ex)(int, char **, int) = 0;
+static int (*py_main)(int, char **) = 0;
+static int *py_ignore_environment_flag = 0;
+
 static const char *run_openslides_code =
     "import openslides_gui.gui;"
     "openslides_gui.gui.main()";
@@ -71,14 +82,94 @@ _get_module_name()
     return NULL;
 }
 
+static void
+_fatal_error(const char *text)
+{
+    MessageBoxA(NULL, text, "Fatal error", MB_OK | MB_ICONERROR);
+    exit(1);
+}
+
+static void
+_fatal_error_fmt(const char *fmt, ...)
+{
+    int size = 512;
+    char *buf  = malloc(size);
+    va_list args;
+    int bytes_written;
+
+    if (!buf)
+	abort();
+
+    va_start(args, fmt);
+    for (;;)
+    {
+	bytes_written = vsnprintf(buf, size, fmt, args);
+	if (bytes_written > -1 && bytes_written < size)
+	    break;
+	else if (bytes_written > size)
+	    size = bytes_written + 1;
+	else
+	    size *= 2;
+
+	buf = realloc(buf, size);
+	if (!buf)
+	    abort();
+    }
+    va_end(args);
+
+    _fatal_error(buf);
+}
+
+static void *
+_load_func(HMODULE module, const char *name)
+{
+    void *address = GetProcAddress(module, name);
+    if (!address)
+	_fatal_error_fmt("Failed to look up symbol %s", name);
+    return address;
+}
+
+static void
+_load_python(const char *pyhome)
+{
+    size_t pyhome_len = strlen(pyhome);
+    size_t size = pyhome_len + strlen(PYTHON_DLL_PATH) + 1;
+    char *buf = malloc(size);
+    HMODULE py_dll;
+
+    if (!buf)
+	abort();
+    memcpy(buf, pyhome, pyhome_len);
+    memcpy(buf + pyhome_len, PYTHON_DLL_PATH, sizeof(PYTHON_DLL_PATH));
+    buf[size - 1] = '\0';
+
+    py_dll = LoadLibrary(buf);
+    if (!py_dll)
+    {
+	DWORD error = GetLastError();
+	_fatal_error_fmt("Failed to load %s (error %d)", buf, error);
+    }
+
+    py_initialize = (void (*)(void))_load_func(py_dll, "Py_Initialize");
+    py_finalize = (void (*)(void))_load_func(py_dll, "Py_Finalize");
+    py_set_program_name = (void (*)(char *))
+	_load_func(py_dll, "Py_SetProgramName");
+    py_set_python_home = (void (*)(char *))
+	_load_func(py_dll, "Py_SetPythonHome");
+    py_run_simple_string_flags = (int (*)(const char *, PyCompilerFlags *))
+	_load_func(py_dll, "PyRun_SimpleStringFlags");
+    py_sys_set_argv_ex = (void (*)(int, char **, int))
+	_load_func(py_dll, "PySys_SetArgvEx");
+    py_main = (int (*)(int, char **))_load_func(py_dll, "Py_Main");
+    py_ignore_environment_flag = (int *)
+	_load_func(py_dll, "Py_IgnoreEnvironmentFlag");
+}
+
 static int
 _run()
 {
-    if (PyRun_SimpleString(run_openslides_code) != 0)
-    {
-	fprintf(stderr, "ERROR: failed to execute openslides\n");
-	return 1;
-    }
+    if (py_run_simple_string_flags(run_openslides_code, NULL) != 0)
+	_fatal_error("Failed to execute openslides");
 
     return 0;
 }
@@ -91,33 +182,33 @@ WinMain(HINSTANCE inst, HINSTANCE prev_inst, LPSTR cmdline, int show)
     int run_py_main = __argc > 1;
     char *py_home, *sep = NULL;
 
-    Py_SetProgramName(__argv[0]);
-
     py_home = _get_module_name();
+    if (!py_home)
+	_fatal_error("Could not determine portable root directory");
 
-    if (py_home)
-	sep = strrchr(py_home, '\\');
+    sep = strrchr(py_home, '\\');
     /* should always be the true */
     if (sep)
-    {
 	*sep = '\0';
-	Py_SetPythonHome(py_home);
-	Py_IgnoreEnvironmentFlag = 1;
-    }
+
+    _load_python(py_home);
+    py_set_program_name(__argv[0]);
+    py_set_python_home(py_home);
+    *py_ignore_environment_flag = 1;
 
     if (run_py_main)
     {
 	/* we where given extra arguments, behave like python.exe */
-	returncode =  Py_Main(__argc, __argv);
+	returncode =  py_main(__argc, __argv);
     }
     else
     {
 	/* no arguments given => start openslides gui */
-	Py_Initialize();
-	PySys_SetArgvEx(__argc, __argv, 0);
+	py_initialize();
+	py_sys_set_argv_ex(__argc, __argv, 0);
 
 	returncode = _run();
-	Py_Finalize();
+	py_finalize();
     }
 
     free(py_home);
diff --git a/extras/win32-portable/openslides.exe b/extras/win32-portable/openslides.exe
index 812eabdc0..7d1bd450f 100755
Binary files a/extras/win32-portable/openslides.exe and b/extras/win32-portable/openslides.exe differ
diff --git a/extras/win32-portable/prepare_portable.py b/extras/win32-portable/prepare_portable.py
index 770fef517..41d81c9e1 100644
--- a/extras/win32-portable/prepare_portable.py
+++ b/extras/win32-portable/prepare_portable.py
@@ -318,7 +318,7 @@ def compile_openslides_launcher():
         return False
 
     cc.add_include_dir(distutils.sysconfig.get_python_inc())
-    cc.add_library_dir(os.path.join(sys.exec_prefix, "Libs"))
+    cc.define_macro("_CRT_SECURE_NO_WARNINGS")
 
     gui_data_dir = os.path.dirname(openslides_gui.__file__)
     gui_data_dir = os.path.join(gui_data_dir, "data")
@@ -343,7 +343,8 @@ def compile_openslides_launcher():
     ])
     cc.link_executable(
         objs, "extras/win32-portable/openslides",
-        extra_preargs=["/subsystem:windows"],
+        extra_preargs=["/subsystem:windows", "/nodefaultlib:python27.lib"],
+        libraries = ["user32"]
     )
     return True
 
@@ -361,7 +362,7 @@ def copy_dlls(odir):
 
     pydllname = "python{0}{1}.dll".format(*sys.version_info[:2])
     src = os.path.join(os.environ["WINDIR"], "System32", pydllname)
-    dest = os.path.join(odir, pydllname)
+    dest = os.path.join(dll_dest, pydllname)
     shutil.copyfile(src, dest)