diff --git a/Linux/LargeVismodule.cpp b/Linux/LargeVismodule.cpp
index bbc50d9..fefda4b 100644
--- a/Linux/LargeVismodule.cpp
+++ b/Linux/LargeVismodule.cpp
@@ -5,6 +5,23 @@ real *out_vec;
 LargeVis model;
 char *filename;
 
+struct module_state {
+	PyObject *error;
+};
+
+#if PY_MAJOR_VERSION >= 3
+#define GETSTATE(m) ((struct module_state*)PyModule_GetState(m))
+#else
+#define GETSTATE(m) (&_state)
+static struct module_state _state;
+#endif
+
+static PyObject *error_out(PyObject *m) {
+    struct module_state *st = GETSTATE(m);
+    PyErr_SetString(st->error, "something bad happened");
+    return NULL;
+}
+
 static PyObject *Run(PyObject *self, PyObject *args)
 {
 	long long out_dim = -1;
@@ -94,7 +111,11 @@ static PyObject *LoadFromList(PyObject *self, PyObject *args)
 		}
 		for (long long j = 0; j < n_dim; ++j)
 		{
+#if PY_MAJOR_VERSION >= 3
+			real x = atof(PyBytes_AS_STRING(PyUnicode_AsUTF8String(PyObject_Str(PyList_GetItem(vec, j)))));
+#else
 			real x = atof(PyString_AsString(PyObject_Str(PyList_GetItem(vec, j))));
+#endif
 			data[ll + j] = x;
 		}
 	}
@@ -116,6 +137,7 @@ static PyObject *SaveToFile(PyObject *self, PyObject *args)
 
 static PyMethodDef PyExtMethods[] =
 {
+	{ "error_out", (PyCFunction)error_out, METH_NOARGS, NULL},
 	{ "run", Run, METH_VARARGS, "(All arguments are optional.\nrun(output dimension, threads number, training samples, propagations number, learning rate, rp-trees number, negative samples number, neighbors number, gamma, perplexity)\nFire up LargeVis." },
 	{ "loadfile", LoadFromFile, METH_VARARGS, "loadfile(str filename)\nLoad high-dimensional feature vectors from file." },
 	{ "loadgraph", LoadFromGraph, METH_VARARGS, "loadfile(str filename)\nLoad graph from file." },
@@ -124,8 +146,58 @@ static PyMethodDef PyExtMethods[] =
 	{ NULL, NULL, 0, NULL }
 };
 
+#if PY_MAJOR_VERSION >= 3
+
+static int Traverse(PyObject *m, visitproc visit, void *arg) {
+    Py_VISIT(GETSTATE(m)->error);
+    return 0;
+}
+
+static int Clear(PyObject *m) {
+    Py_CLEAR(GETSTATE(m)->error);
+    return 0;
+}
+
+
+static struct PyModuleDef moduledef = {
+        PyModuleDef_HEAD_INIT,
+        "LargeVis",
+        NULL,
+        sizeof(struct module_state),
+        PyExtMethods,
+        NULL,
+        Traverse,
+        Clear,
+        NULL
+};
+
+#define INITERROR return NULL
+
+PyMODINIT_FUNC PyInit_LargeVis(void)
+
+#else
+#define INITERROR return
+
 PyMODINIT_FUNC initLargeVis()
+#endif
 {
 	printf("LargeVis successfully imported!\n");
-	Py_InitModule("LargeVis", PyExtMethods);
+#if PY_MAJOR_VERSION >= 3
+    PyObject *module = PyModule_Create(&moduledef);
+#else
+    PyObject *module = Py_InitModule("LargeVis", PyExtMethods);
+#endif
+	if (module == NULL)
+        INITERROR;
+    struct module_state *st = GETSTATE(module);
+
+    st->error = PyErr_NewException("myextension.Error", NULL, NULL);
+    if (st->error == NULL) {
+        Py_DECREF(module);
+        INITERROR;
+    }
+
+#if PY_MAJOR_VERSION >= 3
+    return module;
+#endif
 }
diff --git a/Windows/LargeVismodule.cpp b/Windows/LargeVismodule.cpp
index bbc50d9..fefda4b 100644
--- a/Windows/LargeVismodule.cpp
+++ b/Windows/LargeVismodule.cpp
@@ -5,6 +5,23 @@ real *out_vec;
 LargeVis model;
 char *filename;
 
+struct module_state {
+	PyObject *error;
+};
+
+#if PY_MAJOR_VERSION >= 3
+#define GETSTATE(m) ((struct module_state*)PyModule_GetState(m))
+#else
+#define GETSTATE(m) (&_state)
+static struct module_state _state;
+#endif
+
+static PyObject *error_out(PyObject *m) {
+    struct module_state *st = GETSTATE(m);
+    PyErr_SetString(st->error, "something bad happened");
+    return NULL;
+}
+
 static PyObject *Run(PyObject *self, PyObject *args)
 {
 	long long out_dim = -1;
@@ -94,7 +111,11 @@ static PyObject *LoadFromList(PyObject *self, PyObject *args)
 		}
 		for (long long j = 0; j < n_dim; ++j)
 		{
+#if PY_MAJOR_VERSION >= 3
+			real x = atof(PyBytes_AS_STRING(PyUnicode_AsUTF8String(PyObject_Str(PyList_GetItem(vec, j)))));
+#else
 			real x = atof(PyString_AsString(PyObject_Str(PyList_GetItem(vec, j))));
+#endif
 			data[ll + j] = x;
 		}
 	}
@@ -116,6 +137,7 @@ static PyObject *SaveToFile(PyObject *self, PyObject *args)
 
 static PyMethodDef PyExtMethods[] =
 {
+	{ "error_out", (PyCFunction)error_out, METH_NOARGS, NULL},
 	{ "run", Run, METH_VARARGS, "(All arguments are optional.\nrun(output dimension, threads number, training samples, propagations number, learning rate, rp-trees number, negative samples number, neighbors number, gamma, perplexity)\nFire up LargeVis." },
 	{ "loadfile", LoadFromFile, METH_VARARGS, "loadfile(str filename)\nLoad high-dimensional feature vectors from file." },
 	{ "loadgraph", LoadFromGraph, METH_VARARGS, "loadfile(str filename)\nLoad graph from file." },
@@ -124,8 +146,58 @@ static PyMethodDef PyExtMethods[] =
 	{ NULL, NULL, 0, NULL }
 };
 
+#if PY_MAJOR_VERSION >= 3
+
+static int Traverse(PyObject *m, visitproc visit, void *arg) {
+    Py_VISIT(GETSTATE(m)->error);
+    return 0;
+}
+
+static int Clear(PyObject *m) {
+    Py_CLEAR(GETSTATE(m)->error);
+    return 0;
+}
+
+
+static struct PyModuleDef moduledef = {
+        PyModuleDef_HEAD_INIT,
+        "LargeVis",
+        NULL,
+        sizeof(struct module_state),
+        PyExtMethods,
+        NULL,
+        Traverse,
+        Clear,
+        NULL
+};
+
+#define INITERROR return NULL
+
+PyMODINIT_FUNC PyInit_LargeVis(void)
+
+#else
+#define INITERROR return
+
 PyMODINIT_FUNC initLargeVis()
+#endif
 {
 	printf("LargeVis successfully imported!\n");
-	Py_InitModule("LargeVis", PyExtMethods);
+#if PY_MAJOR_VERSION >= 3
+    PyObject *module = PyModule_Create(&moduledef);
+#else
+    PyObject *module = Py_InitModule("LargeVis", PyExtMethods);
+#endif
+	if (module == NULL)
+        INITERROR;
+    struct module_state *st = GETSTATE(module);
+
+    st->error = PyErr_NewException("myextension.Error", NULL, NULL);
+    if (st->error == NULL) {
+        Py_DECREF(module);
+        INITERROR;
+    }
+
+#if PY_MAJOR_VERSION >= 3
+    return module;
+#endif
 }