diff --git a/docs/source/api.rst b/docs/source/api.rst
index a2b583b..0827257 100644
--- a/docs/source/api.rst
+++ b/docs/source/api.rst
@@ -101,7 +101,7 @@ The MJ shrink conversion map (*MJ縮退マップ*) was also developed alongside
 Transliteration based on NTA shrink mappings
 --------------------------------------------
 
-.. py:function:: jnta_shrink_translit(in_, replacement="\ufffe", passthrough=False)
+.. py:function:: jnta_shrink_translit(in_, replacement="\ufffd", passthrough=False)
 
     Transliterate a Unicode string according to the NTA shrink mappings.
 
diff --git a/src/jntajis/_jntajis.pyi b/src/jntajis/_jntajis.pyi
index b28b02a..6fc9612 100644
--- a/src/jntajis/_jntajis.pyi
+++ b/src/jntajis/_jntajis.pyi
@@ -12,6 +12,6 @@ class TransliterationError(Exception): ...
 def jnta_encode(encoding: str, in_: str, conv_mode: int) -> bytes: ...
 def jnta_decode(encoding: str, in_: bytes) -> str: ...
 def jnta_shrink_translit(
-    in_: str, replacement: str = "\ufffe", passthrough: bool = False
+    in_: str, replacement: str = "\ufffd", passthrough: bool = False
 ) -> str: ...
 def mj_shrink_candidates(in_: str, combo: int, limit: int = 100) -> typing.List[str]: ...
diff --git a/src/jntajis/_jntajis.pyx b/src/jntajis/_jntajis.pyx
index bd46111..8f472ad 100644
--- a/src/jntajis/_jntajis.pyx
+++ b/src/jntajis/_jntajis.pyx
@@ -763,7 +763,7 @@ cdef JNTAJISShrinkingTransliteratorContext_init(
     t.passthrough = passthrough
 
 
-def jnta_shrink_translit(unicode in_, unicode replacement=u"\ufffe", bint passthrough=False):
+def jnta_shrink_translit(unicode in_, unicode replacement=u"\ufffd", bint passthrough=False):
     """
     Transliterate a Unicode string according to the NTA shrink mappings.
     """