diff --git a/usr.bin/more/main.c b/usr.bin/more/main.c
index bb77d0b4c432..3539aa354af5 100644
--- a/usr.bin/more/main.c
+++ b/usr.bin/more/main.c
@@ -51,6 +51,7 @@ static char sccsid[] = "@(#)main.c	8.1 (Berkeley) 6/7/93";
 #include <sys/file.h>
 #include <stdio.h>
 #include <stdlib.h>
+#include <string.h>
 #include <locale.h>
 #include "less.h"
 
diff --git a/usr.bin/more/os.c b/usr.bin/more/os.c
index 75b7a6ee113e..598b1940b355 100644
--- a/usr.bin/more/os.c
+++ b/usr.bin/more/os.c
@@ -54,6 +54,7 @@ static char sccsid[] = "@(#)os.c	8.1 (Berkeley) 6/6/93";
 #include <signal.h>
 #include <setjmp.h>
 #include <stdio.h>
+#include <string.h>
 #include <less.h>
 #include "pathnames.h"
 
diff --git a/usr.bin/more/output.c b/usr.bin/more/output.c
index 5b0a562c4d37..0d015501326e 100644
--- a/usr.bin/more/output.c
+++ b/usr.bin/more/output.c
@@ -42,6 +42,7 @@ static char sccsid[] = "@(#)output.c	8.1 (Berkeley) 6/6/93";
 
 #include <ctype.h>
 #include <stdio.h>
+#include <string.h>
 #include "less.h"
 
 int errmsgs;	/* Count of messages displayed by error() */
diff --git a/usr.bin/more/screen.c b/usr.bin/more/screen.c
index bf12ad62cefb..83352cfed02c 100644
--- a/usr.bin/more/screen.c
+++ b/usr.bin/more/screen.c
@@ -44,6 +44,7 @@ static char sccsid[] = "@(#)screen.c	8.2 (Berkeley) 4/20/94";
  */
 
 #include <stdio.h>
+#include <string.h>
 #include <less.h>
 
 #define TERMIOS 1
diff --git a/usr.bin/more/tags.c b/usr.bin/more/tags.c
index 0d805faff1d1..54865676459c 100644
--- a/usr.bin/more/tags.c
+++ b/usr.bin/more/tags.c
@@ -38,6 +38,7 @@ static char sccsid[] = "@(#)tags.c	8.1 (Berkeley) 6/6/93";
 
 #include <sys/types.h>
 #include <stdio.h>
+#include <string.h>
 #include <less.h>
 
 #define	WHITESP(c)	((c)==' ' || (c)=='\t')