diff -urN arc-5.21o/arcadd.c arc/arcadd.c
--- arc-5.21o/arcadd.c	2005-10-12 17:22:18.000000000 +0200
+++ arc/arcadd.c	2009-12-20 23:04:48.000000000 +0100
@@ -26,6 +26,12 @@
 #include <strings.h>
 #endif
 
+#if	_MTS || SYSV
+#define	rindex	strrchr
+#define	index	strchr
+#endif
+
+
 static	int	addfile();
 int	readhdr(), unlink();
 #if	UNIX
diff -urN arc-5.21o/arcext.c arc/arcext.c
--- arc-5.21o/arcext.c	2005-10-12 17:22:18.000000000 +0200
+++ arc/arcext.c	2009-12-20 23:05:23.000000000 +0100
@@ -26,6 +26,11 @@
 #include <strings.h>
 #endif
 
+#if	_MTS || SYSV
+#define	rindex	strrchr
+#define	index	strchr
+#endif
+
 VOID	openarc(), closearc(), setstamp();
 int	match(), readhdr(), unpack();
 static	VOID	extfile();
diff -urN arc-5.21o/arc.h arc/arc.h
--- arc-5.21o/arc.h	2003-10-31 03:22:36.000000000 +0100
+++ arc/arc.h	2009-12-20 23:06:55.000000000 +0100
@@ -46,10 +46,6 @@
 
 #define	MYBUF	32766		/* Used for fopens and filecopy() */
 
-#if	_MTS || SYSV
-#define	rindex	strrchr
-#define	index	strchr
-#endif
 
 #if	__STDC__
 #include <stdlib.h>
diff -urN arc-5.21o/arcmatch.c arc/arcmatch.c
--- arc-5.21o/arcmatch.c	2003-10-31 03:22:36.000000000 +0100
+++ arc/arcmatch.c	2009-12-20 23:05:41.000000000 +0100
@@ -24,6 +24,12 @@
 #include <strings.h>
 #endif
 
+#if	_MTS || SYSV
+#define	rindex	strrchr
+#define	index	strchr
+#endif
+
+
 VOID	arcdie();
 
 int
diff -urN arc-5.21o/arcmisc.c arc/arcmisc.c
--- arc-5.21o/arcmisc.c	2005-10-09 03:38:22.000000000 +0200
+++ arc/arcmisc.c	2009-12-20 23:06:13.000000000 +0100
@@ -12,6 +12,12 @@
 #include <strings.h>
 #endif
 
+#if	_MTS || SYSV
+#define	rindex	strrchr
+#define	index	strchr
+#endif
+
+
 #if	MSDOS
 #include <dir.h>
 #include <stat.h>
@@ -22,6 +28,8 @@
 #include <osbind.h>
 #include <stat.h>
 
+
+
 VOID 
 exitpause()
 {
diff -urN arc-5.21o/arcrun.c arc/arcrun.c
--- arc-5.21o/arcrun.c	2005-10-12 17:22:18.000000000 +0200
+++ arc/arcrun.c	2009-12-20 23:06:41.000000000 +0100
@@ -26,6 +26,12 @@
 #include <sys/stat.h>
 #endif
 
+#if	_MTS || SYSV
+#define	rindex	strrchr
+#define	index	strchr
+#endif
+
+
 VOID	rempath(), openarc(), closearc(), arcdie();
 int	readhdr(), match(), unpack();
 static	VOID	runfile();