1 files changed, 1 insertions, 0 deletions

diff --git a/src/multibyte/btowc.c b/src/multibyte/btowc.c
index 9d2c3b16..29cb798d 100644
--- a/src/multibyte/btowc.c
+++ b/src/multibyte/btowc.c
@@ -3,5 +3,6 @@
 
 wint_t btowc(int c)
 {
+	c = (unsigned char)c;
 	return c<128U ? c : EOF;
 }