diff --git a/src/vty/buffer.c b/src/vty/buffer.c
index e385f9f..def2f52 100644
--- a/src/vty/buffer.c
+++ b/src/vty/buffer.c
@@ -180,7 +180,7 @@
 }
 
 /* Insert character into the buffer. */
-void buffer_putc(struct buffer *b, u_char c)
+void buffer_putc(struct buffer *b, unsigned char c)
 {
 	buffer_put(b, &c, 1);
 }