diff --git a/lang/pc/libpc/bcp.c b/lang/pc/libpc/bcp.c
index 219c0b158..ef8edf605 100644
--- a/lang/pc/libpc/bcp.c
+++ b/lang/pc/libpc/bcp.c
@@ -18,7 +18,7 @@
 
 /* Author: J.W. Stevenson */
 
-int _bcp(sz,y,x) int sz; char *y,*x; {
+int _bcp(sz,y,x) int sz; unsigned char *y,*x; {
 
 	while (--sz >= 0) {
 		if (*x < *y)