diff --git a/Python/fileutils.c b/Python/fileutils.c
index f137ee936502c1..f262c3e095c9ba 100644
--- a/Python/fileutils.c
+++ b/Python/fileutils.c
@@ -112,7 +112,7 @@ _Py_device_encoding(int fd)
 }
 
 
-static size_t
+static int
 is_valid_wide_char(wchar_t ch)
 {
 #ifdef HAVE_NON_UNICODE_WCHAR_T_REPRESENTATION