diff --git a/Objects/stringlib/find.h b/Objects/stringlib/find.h
index 4cdbb09..38f13ab 100644
--- a/Objects/stringlib/find.h
+++ b/Objects/stringlib/find.h
@@ -103,6 +103,53 @@
 
 #endif /* STRINGLIB_STR */
 
+/*
+This function is a helper for the "find" family (find, rfind, index,
+rindex) of unicodeobject.c file, because they all have the same 
+behaviour for the arguments.
+
+It does not touch the variables received until it knows everything 
+is ok.
+
+Note that we receive a pointer to the pointer of the substring object,
+so when we create that object in this function we don't DECREF it,
+because it continues living in the caller functions (those functions, 
+after finishing using the substring, must DECREF it).
+*/
+
+int 
+_ParseTupleFinds (PyObject *args, PyObject **substring, 
+                  Py_ssize_t *start, Py_ssize_t *end) {
+    PyObject *tmp_substring;
+    Py_ssize_t tmp_start = 0;
+    Py_ssize_t tmp_end = PY_SSIZE_T_MAX;
+    PyObject *obj_start=Py_None, *obj_end=Py_None;
+
+    if (!PyArg_ParseTuple(args, "O|OO:find", &tmp_substring,
+         &obj_start, &obj_end))
+        return 0;
+
+    /* To support None in "start" and "end" arguments, meaning
+       the same as if they were not passed.
+    */
+    if (obj_start != Py_None)
+        if (!_PyEval_SliceIndex(obj_start, &tmp_start))
+            return 0;
+    if (obj_end != Py_None)
+        if (!_PyEval_SliceIndex(obj_end, &tmp_end))
+            return 0;
+
+    tmp_substring = PyUnicode_FromObject(tmp_substring);
+    if (!tmp_substring)
+        return 0;
+
+    *start = tmp_start;
+    *end = tmp_end;
+    *substring = tmp_substring;
+    return 1;
+}
+
+
 #endif /* STRINGLIB_FIND_H */
 
 /*
diff --git a/Objects/stringobject.c b/Objects/stringobject.c
index ce24154..a0e2837 100644
--- a/Objects/stringobject.c
+++ b/Objects/stringobject.c
@@ -1880,10 +1880,21 @@
 	const char *sub;
 	Py_ssize_t sub_len;
 	Py_ssize_t start=0, end=PY_SSIZE_T_MAX;
+	PyObject *obj_start=Py_None, *obj_end=Py_None;
 
-	if (!PyArg_ParseTuple(args, "O|O&O&:find/rfind/index/rindex", &subobj,
-		_PyEval_SliceIndex, &start, _PyEval_SliceIndex, &end))
+	if (!PyArg_ParseTuple(args, "O|OO:find/rfind/index/rindex", &subobj,
+		&obj_start, &obj_end))
 		return -2;
+	/* To support None in "start" and "end" arguments, meaning
+	   the same as if they were not passed.
+	*/
+	if (obj_start != Py_None)
+		if (!_PyEval_SliceIndex(obj_start, &start))
+	        return -2;
+	if (obj_end != Py_None)
+		if (!_PyEval_SliceIndex(obj_end, &end))
+	        return -2;
+
 	if (PyString_Check(subobj)) {
 		sub = PyString_AS_STRING(subobj);
 		sub_len = PyString_GET_SIZE(subobj);
diff --git a/Objects/unicodeobject.c b/Objects/unicodeobject.c
index 1f6f738..06c8fc3 100644
--- a/Objects/unicodeobject.c
+++ b/Objects/unicodeobject.c
@@ -6040,16 +6040,12 @@
 unicode_find(PyUnicodeObject *self, PyObject *args)
 {
     PyObject *substring;
-    Py_ssize_t start = 0;
-    Py_ssize_t end = PY_SSIZE_T_MAX;
+    Py_ssize_t start;
+    Py_ssize_t end;
     Py_ssize_t result;
 
-    if (!PyArg_ParseTuple(args, "O|O&O&:find", &substring,
-		_PyEval_SliceIndex, &start, _PyEval_SliceIndex, &end))
+    if (!_ParseTupleFinds(args, &substring, &start, &end))
         return NULL;
-    substring = PyUnicode_FromObject(substring);
-    if (!substring)
-	return NULL;
 
     result = stringlib_find_slice(
         PyUnicode_AS_UNICODE(self), PyUnicode_GET_SIZE(self),
@@ -6110,15 +6106,11 @@
 {
     Py_ssize_t result;
     PyObject *substring;
-    Py_ssize_t start = 0;
-    Py_ssize_t end = PY_SSIZE_T_MAX;
+    Py_ssize_t start;
+    Py_ssize_t end;
 
-    if (!PyArg_ParseTuple(args, "O|O&O&:index", &substring,
-		_PyEval_SliceIndex, &start, _PyEval_SliceIndex, &end))
+    if (!_ParseTupleFinds(args, &substring, &start, &end))
         return NULL;
-    substring = PyUnicode_FromObject(substring);
-    if (!substring)
-	return NULL;
 
     result = stringlib_find_slice(
         PyUnicode_AS_UNICODE(self), PyUnicode_GET_SIZE(self),
@@ -6781,16 +6773,12 @@
 unicode_rfind(PyUnicodeObject *self, PyObject *args)
 {
     PyObject *substring;
-    Py_ssize_t start = 0;
-    Py_ssize_t end = PY_SSIZE_T_MAX;
+    Py_ssize_t start;
+    Py_ssize_t end;
     Py_ssize_t result;
 
-    if (!PyArg_ParseTuple(args, "O|O&O&:rfind", &substring,
-		_PyEval_SliceIndex, &start, _PyEval_SliceIndex, &end))
-        return NULL;
-    substring = PyUnicode_FromObject(substring);
-    if (!substring)
-	return NULL;
+    if (!_ParseTupleFinds(args, &substring, &start, &end))
+	    return NULL;
 
     result = stringlib_rfind_slice(
         PyUnicode_AS_UNICODE(self), PyUnicode_GET_SIZE(self),
@@ -6812,16 +6800,12 @@
 unicode_rindex(PyUnicodeObject *self, PyObject *args)
 {
     PyObject *substring;
-    Py_ssize_t start = 0;
-    Py_ssize_t end = PY_SSIZE_T_MAX;
+    Py_ssize_t start;
+    Py_ssize_t end;
     Py_ssize_t result;
 
-    if (!PyArg_ParseTuple(args, "O|O&O&:rindex", &substring,
-		_PyEval_SliceIndex, &start, _PyEval_SliceIndex, &end))
-        return NULL;
-    substring = PyUnicode_FromObject(substring);
-    if (!substring)
-	return NULL;
+    if (!_ParseTupleFinds(args, &substring, &start, &end))
+	    return NULL;
 
     result = stringlib_rfind_slice(
         PyUnicode_AS_UNICODE(self), PyUnicode_GET_SIZE(self),