diff --git a/Include/unicodeobject.h b/Include/unicodeobject.h
index b5341875e6f..78e80c7d24b 100644
--- a/Include/unicodeobject.h
+++ b/Include/unicodeobject.h
@@ -1152,11 +1152,11 @@ PyAPI_FUNC(int) _PyUnicode_IsTitlecase(
     );
 
 PyAPI_FUNC(int) _PyUnicode_IsWhitespace(
-    Py_UNICODE ch 	/* Unicode character */
+    const Py_UNICODE ch 	/* Unicode character */
     );
 
 PyAPI_FUNC(int) _PyUnicode_IsLinebreak(
-    Py_UNICODE ch 	/* Unicode character */
+    const Py_UNICODE ch 	/* Unicode character */
     );
 
 PyAPI_FUNC(Py_UNICODE) _PyUnicode_ToLowercase(