diff --git a/mercurial/util.h b/mercurial/util.h
--- a/mercurial/util.h
+++ b/mercurial/util.h
@@ -14,6 +14,47 @@
 #define PyInt_FromLong PyLong_FromLong
 #define PyInt_AsLong PyLong_AsLong
 
+/*
+ Mapping of some of the python < 2.x PyString* functions to py3k's PyUnicode.
+
+ The commented names below represent those that are present in the PyBytes
+ definitions for python < 2.6 (below in this file) that don't have a direct
+ implementation.
+*/
+
+#define PyStringObject PyUnicodeObject
+#define PyString_Type PyUnicode_Type
+
+#define PyString_Check PyUnicode_Check
+#define PyString_CheckExact PyUnicode_CheckExact
+#define PyString_CHECK_INTERNED PyUnicode_CHECK_INTERNED
+#define PyString_AS_STRING PyUnicode_AsLatin1String
+#define PyString_GET_SIZE PyUnicode_GET_SIZE
+
+#define PyString_FromStringAndSize PyUnicode_FromStringAndSize
+#define PyString_FromString PyUnicode_FromString
+#define PyString_FromFormatV PyUnicode_FromFormatV
+#define PyString_FromFormat PyUnicode_FromFormat
+/* #define PyString_Size PyUnicode_GET_SIZE */
+/* #define PyString_AsString */
+/* #define PyString_Repr */
+#define PyString_Concat PyUnicode_Concat
+#define PyString_ConcatAndDel PyUnicode_AppendAndDel
+#define _PyString_Resize PyUnicode_Resize
+/* #define _PyString_Eq */
+#define PyString_Format PyUnicode_Format
+/* #define _PyString_FormatLong */
+/* #define PyString_DecodeEscape */
+#define _PyString_Join PyUnicode_Join
+#define PyString_Decode PyUnicode_Decode
+#define PyString_Encode PyUnicode_Encode
+#define PyString_AsEncodedObject PyUnicode_AsEncodedObject
+#define PyString_AsEncodedString PyUnicode_AsEncodedString
+#define PyString_AsDecodedObject PyUnicode_AsDecodedObject
+#define PyString_AsDecodedString PyUnicode_AsDecodedUnicode
+/* #define PyString_AsStringAndSize */
+#define _PyString_InsertThousandsGrouping _PyUnicode_InsertThousandsGrouping
+
 #endif /* PY_MAJOR_VERSION */
 
 /* Backports from 2.6 */