diff --git a/Objects/stringlib/string_format.h b/Objects/stringlib/string_format.h
index 37bd370..3f44e96 100644
--- a/Objects/stringlib/string_format.h
+++ b/Objects/stringlib/string_format.h
@@ -766,6 +766,10 @@
         return PyObject_Repr(obj);
     case 's':
         return STRINGLIB_TOSTR(obj);
+#if PY_VERSION_HEX >= 0x03000000
+    case 'a':
+        return STRINGLIB_TOASCII(obj);
+#endif
     default:
 	if (conversion > 32 && conversion < 127) {
 		/* It's the ASCII subrange; casting to char is safe
diff --git a/Objects/stringlib/stringdefs.h b/Objects/stringlib/stringdefs.h
index bdc3a29..946de05 100644
--- a/Objects/stringlib/stringdefs.h
+++ b/Objects/stringlib/stringdefs.h
@@ -24,5 +24,5 @@
 #define STRINGLIB_CMP            memcmp
 #define STRINGLIB_TOSTR          PyObject_Str
 #define STRINGLIB_GROUPING       _PyBytes_InsertThousandsGrouping
-
+#define STRINGLIB_TOASCII        PyObject_Repr
 #endif /* !STRINGLIB_STRINGDEFS_H */
diff --git a/Objects/stringlib/unicodedefs.h b/Objects/stringlib/unicodedefs.h
index 8f87fe0..d579c1c 100644
--- a/Objects/stringlib/unicodedefs.h
+++ b/Objects/stringlib/unicodedefs.h
@@ -25,8 +25,10 @@
 
 #if PY_VERSION_HEX < 0x03000000
 #define STRINGLIB_TOSTR          PyObject_Unicode
+#define STRINGLIB_TOASCII        PyObject_Repr
 #else
 #define STRINGLIB_TOSTR          PyObject_Str
+#define STRINGLIB_TOASCII        PyObject_ASCII
 #endif
 
 #define STRINGLIB_WANT_CONTAINS_OBJ 1