--- get/getx11/XGetHClrs.c
+++ get/getx11/XGetHClrs.c
@@ -1,5 +1,4 @@
 #ifndef XLIBINT_H_NOT_AVAILABLE
-#include <X11/copyright.h>
 
 /* $XConsortium: XGetHClrs.c,v 11.10 88/09/06 16:07:50 martin Exp $ */
 /* Copyright    Massachusetts Institute of Technology    1986	*/
--- tools/mallocNd.c
+++ tools/mallocNd.c
@@ -67,7 +67,7 @@
 
 /* Imports */
 #include <stdio.h>
-extern char *malloc();
+#include <string.h>
 
 /* Forward declarations */
 char *BuildIndirectionTable();
--- tools/into.c
+++ tools/into.c
@@ -40,8 +40,8 @@
 static char buf[MAXPATHLEN+1];
 short forceflg;				/* overwrite an unwritable file? */
 
-extern int errno;
-extern char *sys_errlist[];
+#include <errno.h>
+#include <string.h>
 
 void
 main(argc, argv)
@@ -103,7 +103,7 @@
     if (ferror(outf))
     {
 	fprintf(stderr, "into: %s, \"%s\" not modified\n",
-	    sys_errlist[errno], argv[1]);
+	    strerror(errno), argv[1]);
 	unlink(buf);
 	exit(1);
     }
--- cnv/tex/dvirle2.c
+++ cnv/tex/dvirle2.c
@@ -55,7 +55,6 @@
 void DumpTopOfBand(), MoveDown(), WriteBuf(), WriteBlanks();
 
 char	*ProgName;
-extern int errno;
 extern char *optarg;
 extern int optind;
 
--- cnv/wasatchrle.c
+++ cnv/wasatchrle.c
@@ -32,7 +32,6 @@
 #include <errno.h>
 #include "rle.h"
 
-extern int errno;
 
 /* "short" in our world is 16 bits.  Beware of swyte-bopping. */
 
--- get/getx11/x11_stuff.c
+++ get/getx11/x11_stuff.c
@@ -155,7 +155,6 @@
 			IPC_CREAT|0777 );
 	    if ( img->shm_img.shmid < 0 )
 	    {
-		extern int errno;
 		if ( errno == ENOSPC )
 		{
 		    if ( !no_shared_space )
@@ -361,7 +360,6 @@ Boolean reallocate;
 	    XDestroyImage( image );
 	    if ( img->shm_pix.shmid < 0 )
 	    {
-		extern int errno;
 		if ( errno == ENOSPC )
 		{
 		    if ( !no_shared_space )
--- get/qcr/qcr.h
+++ get/qcr/qcr.h
@@ -6,8 +6,6 @@
 #define GREEN 1
 #define BLUE 2
 
-extern int errno;
-
 /* Command defs for QCR-Z Film Recorder */
 
 /* These are for 8 bit Look Up Tables */
--- get/gettaac.c
+++ get/gettaac.c
@@ -24,6 +24,7 @@
  * Send bug fixes and improvements to:  ksp@maxwell.nde.swri.edu
  */
 
+#include <errno.h>
 #include <stdio.h>
 #include <strings.h>
 #include <signal.h>
@@ -459,7 +460,6 @@ char    *template;
      char    nonUnique;
      char    twiddleUserCompletion;
 
-     extern  int         errno;
      struct  direct     *nameEntry;
      DIR                *dirChan;
      struct  passwd     *pwdEntry;
--- tools/clock/rleClock.c
+++ tools/clock/rleClock.c
@@ -598,7 +598,7 @@
     { TRUE,  "-tf", STRING, "Text area format string", 	          (char *)&FormatString }, 
     { FALSE, "-Xm", BOOL,   "Output the alpha channel on RGB",    (char *)&DebugAlpha },
     { FALSE, "-D",  BOOL,   "Turn on debugging",	          (char *)&Debug },
-    NULL
+    { FALSE, NULL }
 };
 
 void
--- tools/to8.c
+++ tools/to8.c
@@ -175,7 +175,7 @@
 	 * Give it a background color of black, since the real background
 	 * will be dithered anyway.
 	 */
-	if ( in_hdr.background != NULL )
+	if ( in_hdr.background != 0 )
 	{
 	    out_hdr.bg_color = (int *)malloc( sizeof( int ) );
 	    RLE_CHECK_ALLOC( cmd_name( argv ), out_hdr.bg_color, 0 );
--- cnv/rletoabA62/rletoabA62.c
+++ cnv/rletoabA62/rletoabA62.c
@@ -157,7 +157,7 @@
 	exit(1);
     }
     if (optind < argc) {
-	if ((file = open(argv[optind], 0)) == NULL) {
+	if ((file = open(argv[optind], 0)) == -1) {
 	    perror(argv[optind]);
 	    exit(1);
 	}
