diff --git a/usr.bin/calendar/Makefile b/usr.bin/calendar/Makefile
index 13cc6763944a..1473d04009d9 100644
--- a/usr.bin/calendar/Makefile
+++ b/usr.bin/calendar/Makefile
@@ -3,7 +3,8 @@
 
 PROG=	calendar
 SRCS=   calendar.c io.c day.c ostern.c paskha.c
-CFLAGS+= -Wall
+WARNS?=		2
+NO_WERROR=	yes
 INTER=          de_DE.ISO8859-1 hr_HR.ISO8859-2 ru_RU.KOI8-R
 DE_LINKS=       de_DE.ISO_8859-1 de_DE.ISO8859-15 de_DE.ISO_8859-15
 HR_LINKS=       hr_HR.ISO_8859-2
diff --git a/usr.bin/calendar/calendar.c b/usr.bin/calendar/calendar.c
index 197b82d7d0b7..8a900f9512e4 100644
--- a/usr.bin/calendar/calendar.c
+++ b/usr.bin/calendar/calendar.c
@@ -29,19 +29,21 @@
  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
- *
- * $FreeBSD$
  */
 
+#include <sys/cdefs.h>
+
+__FBSDID("$FreeBSD$");
+
 #ifndef lint
 static const char copyright[] =
 "@(#) Copyright (c) 1989, 1993\n\
 	The Regents of the University of California.  All rights reserved.\n";
-#endif /* not lint */
+#endif
 
 #ifndef lint
 static const char sccsid[] = "@(#)calendar.c  8.3 (Berkeley) 3/25/94";
-#endif /* not lint */
+#endif
 
 #include <err.h>
 #include <errno.h>
diff --git a/usr.bin/calendar/calendar.h b/usr.bin/calendar/calendar.h
index 2e7adfa15d21..e8622109ee23 100644
--- a/usr.bin/calendar/calendar.h
+++ b/usr.bin/calendar/calendar.h
@@ -38,7 +38,7 @@ extern struct passwd *pw;
 extern int doall;
 extern struct iovec header[];
 extern struct tm *tp;
-extern char *calendarFile;
+extern const char *calendarFile;
 extern char *optarg;
 
 void	 cal __P((void));
diff --git a/usr.bin/calendar/day.c b/usr.bin/calendar/day.c
index 16b17d73f7df..44f8bb400368 100644
--- a/usr.bin/calendar/day.c
+++ b/usr.bin/calendar/day.c
@@ -29,21 +29,22 @@
  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
- *
- * $FreeBSD$
  */
 
+#include <sys/cdefs.h>
 
+__FBSDID("$FreeBSD$");
+
+#include <sys/types.h>
+#include <sys/uio.h>
 #include <ctype.h>
+#include <err.h>
 #include <locale.h>
 #include <stdio.h>
-#include <string.h>
-#include <sys/types.h>
-#include <time.h>
-#include <sys/uio.h>
-#include <string.h>
 #include <stdlib.h>
-#include <err.h>
+#include <string.h>
+#include <string.h>
+#include <time.h>
 
 #include "pathnames.h"
 #include "calendar.h"
@@ -59,11 +60,11 @@ int daytab[][14] = {
 	{ 0, -1, 30, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365 },
 };
 
-static char *days[] = {
+static char const *days[] = {
 	"sun", "mon", "tue", "wed", "thu", "fri", "sat", NULL,
 };
 
-static char *months[] = {
+static const char *months[] = {
 	"jan", "feb", "mar", "apr", "may", "jun",
 	"jul", "aug", "sep", "oct", "nov", "dec", NULL,
 };
@@ -391,9 +392,9 @@ isnow(endp, monthp, dayp, varp)
 
 int
 getmonth(s)
-	register char *s;
+	char *s;
 {
-	register char **p;
+	const char **p;
 	struct fixs *n;
 
 	for (n = fnmonths; n->name; ++n)
@@ -411,9 +412,9 @@ getmonth(s)
 
 int
 getday(s)
-	register char *s;
+	char *s;
 {
-	register char **p;
+	const char **p;
 	struct fixs *n;
 
 	for (n = fndays; n->name; ++n)
@@ -435,24 +436,24 @@ getday(s)
  */
 int
 getdayvar(s)
-	register char *s;
+	char *s;
 {
-	register int offset;
+	int offs;
 
 
-	offset = strlen(s);
+	offs = strlen(s);
 
 
 	/* Sun+1 or Wednesday-2
 	 *    ^              ^   */
 
-	/* fprintf(stderr, "x: %s %s %d\n", s, s + offset - 2, offset); */
-	switch(*(s + offset - 2)) {
+	/* fprintf(stderr, "x: %s %s %d\n", s, s + offs - 2, offs); */
+	switch(*(s + offs - 2)) {
 	case '-':
-	    return(-(atoi(s + offset - 1)));
+	    return(-(atoi(s + offs - 1)));
 	    break;
 	case '+':
-	    return(atoi(s + offset - 1));
+	    return(atoi(s + offs - 1));
 	    break;
 	}
 
@@ -462,15 +463,15 @@ getdayvar(s)
 	 */
 
 	/* last */
-	if      (offset > 4 && !strcasecmp(s + offset - 4, "last"))
+	if      (offs > 4 && !strcasecmp(s + offs - 4, "last"))
 	    return(-1);
-	else if (offset > 5 && !strcasecmp(s + offset - 5, "first"))
+	else if (offs > 5 && !strcasecmp(s + offs - 5, "first"))
 	    return(+1);
-	else if (offset > 6 && !strcasecmp(s + offset - 6, "second"))
+	else if (offs > 6 && !strcasecmp(s + offs - 6, "second"))
 	    return(+2);
-	else if (offset > 5 && !strcasecmp(s + offset - 5, "third"))
+	else if (offs > 5 && !strcasecmp(s + offs - 5, "third"))
 	    return(+3);
-	else if (offset > 6 && !strcasecmp(s + offset - 6, "fourth"))
+	else if (offs > 6 && !strcasecmp(s + offs - 6, "fourth"))
 	    return(+4);
 
 
diff --git a/usr.bin/calendar/io.c b/usr.bin/calendar/io.c
index 91e3f514a766..51b539c75ed5 100644
--- a/usr.bin/calendar/io.c
+++ b/usr.bin/calendar/io.c
@@ -29,44 +29,46 @@
  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
- *
- * $FreeBSD$
  */
 
+#include <sys/cdefs.h>
+
+__FBSDID("$FreeBSD$");
+
 #ifndef lint
 static const char copyright[] =
 "@(#) Copyright (c) 1989, 1993\n\
 	The Regents of the University of California.  All rights reserved.\n";
-#endif /* not lint */
+#endif
 
 #ifndef lint
 static const char sccsid[] = "@(#)calendar.c  8.3 (Berkeley) 3/25/94";
-#endif /* not lint */
+#endif
 
-#include <sys/param.h>
-#include <stdio.h>
-#include <ctype.h>
 #include <sys/types.h>
+#include <sys/param.h>
 #include <sys/stat.h>
-#include <unistd.h>
+#include <sys/time.h>
+#include <sys/uio.h>
+#include <sys/wait.h>
+#include <ctype.h>
 #include <err.h>
 #include <errno.h>
 #include <langinfo.h>
 #include <locale.h>
-#include <string.h>
-#include <sys/uio.h>
-#include <sys/time.h>
-#include <stdlib.h>
 #include <pwd.h>
-#include <sys/wait.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
 
 #include "pathnames.h"
 #include "calendar.h"
 
 
-char *calendarFile = "calendar";  /* default calendar file */
-char *calendarHome = ".calendar"; /* HOME */
-char *calendarNoMail = "nomail";  /* don't sent mail if this file exist */
+const char *calendarFile = "calendar";  /* default calendar file */
+const char *calendarHome = ".calendar"; /* HOME */
+const char *calendarNoMail = "nomail";  /* don't sent mail if this file exist */
 
 struct fixs neaster, npaskha;
 
@@ -84,8 +86,8 @@ struct iovec header[] = {
 void
 cal()
 {
-	register int printing;
-	register char *p;
+	int printing;
+	char *p;
 	FILE *fp;
 	int ch, l;
 	int month;
diff --git a/usr.bin/calendar/ostern.c b/usr.bin/calendar/ostern.c
index 21c6c739799a..bf7f366a81a5 100644
--- a/usr.bin/calendar/ostern.c
+++ b/usr.bin/calendar/ostern.c
@@ -22,10 +22,12 @@
  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
- *
- * $FreeBSD$
  */
 
+#include <sys/cdefs.h>
+
+__FBSDID("$FreeBSD$");
+
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -76,7 +78,7 @@ geteaster(s, year)
 	char *s;
         int year;
 {
-	register int offset = 0;
+	int offset = 0;
 	extern struct fixs neaster;
 
 #define EASTER "easter"
diff --git a/usr.bin/calendar/paskha.c b/usr.bin/calendar/paskha.c
index e107e18df329..c5b31ba5008f 100644
--- a/usr.bin/calendar/paskha.c
+++ b/usr.bin/calendar/paskha.c
@@ -22,10 +22,12 @@
  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
- *
- * $FreeBSD$
  */
 
+#include <sys/cdefs.h>
+
+__FBSDID("$FreeBSD$");
+
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -36,6 +38,8 @@
 #define PASKHA "paskha"
 #define PASKHALEN (sizeof(PASKHA) - 1)
 
+static int paskha (int);
+
 /* return year day for Orthodox Easter using Gauss formula */
 /* (old style result) */