--- a/pr/src/misc/prerrortable.c
+++ b/pr/src/misc/prerrortable.c
@@ -29,16 +29,19 @@ used in advertising or publicity pertain
 of the software without specific, written prior permission.
 M.I.T. and the M.I.T. S.I.P.B. make no representations about
 the suitability of this software for any purpose.  It is
 provided "as is" without express or implied warranty.
 
 */
 
 #include <string.h>
+#ifdef SUNOS4
+#include "md/sunos4.h"  /* for strerror */
+#endif
 #include <assert.h>
 #include <errno.h>
 #include "prmem.h"
 #include "prerror.h"
 #include "prerrorplugin.h"
 
 #define	ERRCODE_RANGE	8	/* # of bits to shift table number */
 #define	BITS_PER_CHAR	6	/* # bits to shift per character in name */