--- adbuf.c.org	2010-05-11 10:34:35.000000000 +0200
+++ adbuf.c	2010-05-11 10:34:54.000000000 +0200
@@ -127,7 +127,7 @@
 	if (adbuf_ptr(b) == NULL)
 		return 1; /* bad buffer in input */
 	if (b->left >= 2) {
-		unsigned char *p = b->buf + adbuf_used(b);
+		unsigned char *p = (unsigned char *) (b->buf + adbuf_used(b));
 
 		*p = c;
 		*(p+1) = '\0';