diff --git a/pep-3138.txt b/pep-3138.txt
index 11a422443..d100fc205 100644
--- a/pep-3138.txt
+++ b/pep-3138.txt
@@ -99,7 +99,7 @@ Specification
    (0xd800-0xdbff, but not followed by 0xdc00-0xdfff) to '\\uXXXX'.
 
  * Convert non-printable characters(Py_UNICODE_ISPRINTABLE() returns 0)
-   to 'xXX', '\\uXXXX' or '\\U00xxxxxx'.
+   to '\\xXX', '\\uXXXX' or '\\U00xxxxxx'.
 
  * Backslash-escape quote characters (apostrophe, 0x27) and add quote
    character at the beginning and the end.