diff -up arc-5.21p/arclzw.c~ arc-5.21p/arclzw.c
--- arc-5.21p/arclzw.c~	2010-08-07 15:06:42.000000000 +0200
+++ arc-5.21p/arclzw.c	2020-02-15 10:34:25.469210421 +0100
@@ -57,9 +57,10 @@ static VOID     putcode();
 #define NOT_FND  0xFFFF
 
 extern u_char	*pinbuf;
+extern u_char	*outend; 
+extern u_char	*outbuf;
 u_char		*inbeg, *inend;
-u_char          *outbuf;
-u_char          *outbeg, *outend; 
+u_char          *outbeg;
 
 static int      sp;		/* current stack pointer */
 static int	inflag;
diff -up arc-5.21p/arcunp.c~ arc-5.21p/arcunp.c
--- arc-5.21p/arcunp.c~	2010-08-07 15:06:42.000000000 +0200
+++ arc-5.21p/arcunp.c	2020-02-15 10:33:15.751795541 +0100
@@ -33,14 +33,14 @@ VOID	arcdie(), codebuf();
 
 extern u_char   state;		/* repeat unpacking state */
 extern int	lastc;
+extern short    crcval;		/* CRC check value */
+extern long     stdlen;		/* bytes to read */
 
 /* repeat unpacking states */
 
 #define NOHIST 0		/* no relevant history */
 #define INREP 1			/* sending a repeated value */
 
-short    crcval;		/* CRC check value */
-long     stdlen;		/* bytes to read */
 #if	!DOS
 static int	gotcr;		/* got a carriage return? */
 #endif