@@ -1066,6 +1066,9 @@ def test_partition(self):
         self.checkraises(ValueError, S, 'partition', '')
         self.checkraises(TypeError, S, 'partition', None)
 
+        # mixed use of str and unicode
+        self.assertEqual('a/b/c'.partition(u'/'), ('a', '/', 'b/c'))
+
     def test_rpartition(self):
 
         self.checkequal(('this is the rparti', 'ti', 'on method'),
@@ -1081,6 +1084,8 @@ def test_rpartition(self):
         self.checkraises(ValueError, S, 'rpartition', '')
         self.checkraises(TypeError, S, 'rpartition', None)
 
+        # mixed use of str and unicode
+        self.assertEqual('a/b/c'.rpartition(u'/'), ('a/b', '/', 'c'))
 
 class MixinStrStringUserStringTest:
     # Additional tests for 8bit strings, i.e. str, UserString and
 
@@ -12,6 +12,9 @@ What's New in Python 2.5.3?
 Core and builtins
 -----------------
 
+- Issue #3751: str.rpartition would perform a left-partition when called with
+  a unicode argument.
+
 - Issue #3537: Fix an assertion failure when an empty but presized dict
   object was stored in the freelist.
 
 
@@ -1595,7 +1595,7 @@ string_rpartition(PyStringObject *self, PyObject *sep_obj)
 	}
 #ifdef Py_USING_UNICODE
 	else if (PyUnicode_Check(sep_obj))
-		return PyUnicode_Partition((PyObject *) self, sep_obj);
+		return PyUnicode_RPartition((PyObject *) self, sep_obj);
 #endif
 	else if (PyObject_AsCharBuffer(sep_obj, &sep, &sep_len))
 		return NULL;
Original file line number	Diff line number	Diff line change
`@@ -1595,7 +1595,7 @@ string_rpartition(PyStringObject self, PyObject sep_obj)`
`1595`	`1595`	`}`
`1596`	`1596`	`#ifdef Py_USING_UNICODE`
`1597`	`1597`	`else if (PyUnicode_Check(sep_obj))`
`1598`		`- return PyUnicode_Partition((PyObject *) self, sep_obj);`
	`1598`	`+ return PyUnicode_RPartition((PyObject *) self, sep_obj);`
`1599`	`1599`	`#endif`
`1600`	`1600`	`else if (PyObject_AsCharBuffer(sep_obj, &sep, &sep_len))`
`1601`	`1601`	`return NULL;`