diff --git a/usr.bin/calendar/calendar.1 b/usr.bin/calendar/calendar.1
index eeadc92152b7..8abaf2096ef1 100644
--- a/usr.bin/calendar/calendar.1
+++ b/usr.bin/calendar/calendar.1
@@ -28,7 +28,7 @@
 .\"     @(#)calendar.1  8.1 (Berkeley) 6/29/93
 .\" $FreeBSD$
 .\"
-.Dd October 28, 2020
+.Dd November 4, 2020
 .Dt CALENDAR 1
 .Os
 .Sh NAME
@@ -218,12 +218,14 @@ If the shared file is not referenced by a full pathname,
 searches in the current (or home) directory first, and then in the
 directory
 .Pa /usr/share/calendar .
-Empty lines and lines protected by the C commenting syntax
+Empty lines and text protected by the C commenting syntax
 .Pq Li /* ... */
+or
+.Pq Li //
 are ignored.
 .Pp
 Some possible calendar entries (<tab> characters highlighted by
-\fB\et\fR sequence)
+\fB\et\fR sequence):
 .Bd -unfilled -offset indent
 LANG=C
 Easter=Ostern
diff --git a/usr.bin/calendar/calendar.h b/usr.bin/calendar/calendar.h
index 2604568352b5..312ef1c2d4c9 100644
--- a/usr.bin/calendar/calendar.h
+++ b/usr.bin/calendar/calendar.h
@@ -122,7 +122,7 @@ extern int	year1, year2;
  * - Use event_continue() to add more text to the last added event
  * - Use event_print_all() to display them in time chronological order
  */
-struct event *event_add(int, int, int, char *, int, char *, char *);
+struct event *event_add(int, int, int, int, char *, char *);
 void	event_continue(struct event *events, char *txt);
 void	event_print_all(FILE *fp);
 struct event {
@@ -189,7 +189,7 @@ int	remember_yd(int y, int d, int *rm, int *rd);
 int	first_dayofweek_of_year(int y);
 int	first_dayofweek_of_month(int y, int m);
 int	walkthrough_dates(struct event **e);
-void	addtodate(struct event *e, int year, int month, int day);
+void	addtodate(struct event *e);
 
 /* pom.c */
 #define	MAXMOONS	18
diff --git a/usr.bin/calendar/dates.c b/usr.bin/calendar/dates.c
index 6ba4e3a4a6f2..740187c48463 100644
--- a/usr.bin/calendar/dates.c
+++ b/usr.bin/calendar/dates.c
@@ -444,12 +444,12 @@ find_day(int yy, int mm, int dd)
 }
 
 void
-addtodate(struct event *e, int year, int month, int day)
+addtodate(struct event *e)
 {
 	struct cal_day *d;
 	struct event *ee;
 
-	d = find_day(year, month, day);
+	d = find_day(e->year, e->month, e->day);
 	ee = d->lastevent;
 	if (ee != NULL)
 		ee->next = e;
diff --git a/usr.bin/calendar/events.c b/usr.bin/calendar/events.c
index 39ede509e4db..9d4dce97e6e0 100644
--- a/usr.bin/calendar/events.c
+++ b/usr.bin/calendar/events.c
@@ -39,6 +39,7 @@ __FBSDID("$FreeBSD$");
 #include <iconv.h>
 #include <errno.h>
 #include <langinfo.h>
+#include <locale.h>
 
 static iconv_t conv = (iconv_t)-1;
 static char *currentEncoding = NULL;
@@ -150,8 +151,7 @@ convert(char *input)
 }
 
 struct event *
-event_add(int year, int month, int day, char *date, int var, char *txt,
-    char *extra)
+event_add(int year, int month, int day, int var, char *txt, char *extra)
 {
 	struct event *e;
 
@@ -159,25 +159,22 @@ event_add(int year, int month, int day, char *date, int var, char *txt,
 	 * Creating a new event:
 	 * - Create a new event
 	 * - Copy the machine readable day and month
-	 * - Copy the human readable and language specific date
 	 * - Copy the text of the event
 	 */
 	e = (struct event *)calloc(1, sizeof(struct event));
 	if (e == NULL)
 		errx(1, "event_add: cannot allocate memory");
+	e->year = year;
 	e->month = month;
 	e->day = day;
 	e->var = var;
-	e->date = convert(date);
-	if (e->date == NULL)
-		errx(1, "event_add: cannot allocate memory");
 	e->text = convert(txt);
 	if (e->text == NULL)
 		errx(1, "event_add: cannot allocate memory");
 	e->extra = NULL;
 	if (extra != NULL && extra[0] != '\0')
 		e->extra = convert(extra);
-	addtodate(e, year, month, day);
+	addtodate(e);
 	return (e);
 }
 
@@ -204,20 +201,37 @@ void
 event_print_all(FILE *fp)
 {
 	struct event *e;
+	struct tm tm;
+	char dbuf[80];
+	static int d_first;
+	const char *lang;
+
+	lang = getenv("LANG");
+	if (lang == NULL)
+		lang = "C";
+	if (setlocale(LC_ALL, lang) == NULL)
+		(void)setlocale(LC_ALL, "C");
+	d_first = (*nl_langinfo(D_MD_ORDER) == 'd');
 
 	while (walkthrough_dates(&e) != 0) {
+		if (e) {
 #ifdef DEBUG
-		if (e)
 			fprintf(stderr, "event_print_all month: %d, day: %d\n",
 			    e->month, e->day);
 #endif
+			memset(&tm, 0, sizeof(struct tm));
+			tm.tm_mday = e->day;
+			tm.tm_mon = e->month - 1;
+			tm.tm_year = e->year - 1900;
+			(void)strftime(dbuf, sizeof(dbuf), d_first ? "%e %b" : "%b %e", &tm);
+		}
 
 		/*
 		 * Go through all events and print the text of the matching
 		 * dates
 		 */
 		while (e != NULL) {
-			(void)fprintf(fp, "%s%c%s%s%s%s\n", e->date,
+			(void)fprintf(fp, "%s%c%s%s%s%s\n", dbuf,
 			    e->var ? '*' : ' ', e->text,
 			    e->extra != NULL ? " (" : "",
 			    e->extra != NULL ? e->extra : "",
diff --git a/usr.bin/calendar/io.c b/usr.bin/calendar/io.c
index 27bd55db3619..e6a69581a342 100644
--- a/usr.bin/calendar/io.c
+++ b/usr.bin/calendar/io.c
@@ -50,7 +50,6 @@ __FBSDID("$FreeBSD$");
 #include <ctype.h>
 #include <err.h>
 #include <errno.h>
-#include <langinfo.h>
 #include <locale.h>
 #include <pwd.h>
 #include <stdbool.h>
@@ -159,7 +158,9 @@ cal_path(void)
 {
 	static char buffer[MAXPATHLEN + 10];
 
-	if (cal_dir[0] == '/')
+	if (cal_dir == NULL)
+		snprintf(buffer, sizeof(buffer), "%s", cal_file);
+	else if (cal_dir[0] == '/')
 		snprintf(buffer, sizeof(buffer), "%s/%s", cal_dir, cal_file);
 	else
 		snprintf(buffer, sizeof(buffer), "%s/%s/%s", cal_home, cal_dir, cal_file);
@@ -181,14 +182,14 @@ token(char *line, FILE *out, int *skip, int *unskip)
 	int this_cal_line;
 
 	if (strncmp(line, "endif", 5) == 0) {
-		if (*skip > 0)
-			--*skip;
-		else if (*unskip > 0)
-			--*unskip;
-		else {
+		if (*skip + *unskip == 0) {
 			WARN0("#endif without prior #ifdef or #ifndef");
 			return (T_ERR);
 		}
+		if (*skip > 0)
+			--*skip;
+		else
+			--*unskip;
 
 		return (T_OK);
 	}
@@ -247,18 +248,17 @@ token(char *line, FILE *out, int *skip, int *unskip)
 			WARN0("Expecting no arguments after #else");
 			return (T_ERR);
 		}
+		if (*skip + *unskip == 0) {
+			WARN0("#else without prior #ifdef or #ifndef");
+			return (T_ERR);
+		}
 
-		if (*unskip == 0) {
-			if (*skip == 0) {
-				WARN0("#else without prior #ifdef or #ifndef");
-				return (T_ERR);
-			} else if (*skip == 1) {
-				*skip = 0;
-				*unskip = 1;
-			}
-		} else if (*unskip == 1) {
-			*skip = 1;
-			*unskip = 0;
+		if (*skip == 0) {
+			++*skip;
+			--*unskip;
+		} else if (*skip == 1) {
+			--*skip;
+			++*unskip;
 		}
 
 		return (T_OK);
@@ -366,7 +366,6 @@ cal_parse(FILE *in, FILE *out)
 	size_t linecap = 0;
 	ssize_t linelen;
 	ssize_t l;
-	static int d_first = -1;
 	static int count = 0;
 	int i;
 	int month[MAXCOUNT];
@@ -374,19 +373,11 @@ cal_parse(FILE *in, FILE *out)
 	int year[MAXCOUNT];
 	int skip = 0;
 	int unskip = 0;
-	char dbuf[80];
 	char *pp, p;
-	struct tm tm;
 	int flags;
 	char *c, *cc;
 	bool incomment = false;
 
-	/* Unused */
-	tm.tm_sec = 0;
-	tm.tm_min = 0;
-	tm.tm_hour = 0;
-	tm.tm_wday = 0;
-
 	if (in == NULL)
 		return (1);
 
@@ -468,7 +459,7 @@ cal_parse(FILE *in, FILE *out)
 		 * and does not run iconv(), this variable has little use.
 		 */
 		if (strncmp(buf, "LANG=", 5) == 0) {
-			(void)setlocale(LC_CTYPE, buf + 5);
+			(void)setlocale(LC_ALL, buf + 5);
 #ifdef WITH_ICONV
 			if (!doall)
 				set_new_encoding();
@@ -532,18 +523,10 @@ cal_parse(FILE *in, FILE *out)
 		while (pp[1] == '\t')
 			pp++;
 
-		if (d_first < 0)
-			d_first = (*nl_langinfo(D_MD_ORDER) == 'd');
-
 		for (i = 0; i < count; i++) {
-			tm.tm_mon = month[i] - 1;
-			tm.tm_mday = day[i];
-			tm.tm_year = year[i] - 1900;
-			(void)strftime(dbuf, sizeof(dbuf),
-			    d_first ? "%e %b" : "%b %e", &tm);
 			if (debug)
 				WARN1("got \"%s\"", pp);
-			events[i] = event_add(year[i], month[i], day[i], dbuf,
+			events[i] = event_add(year[i], month[i], day[i],
 			    ((flags &= F_VARIABLE) != 0) ? 1 : 0, pp,
 			    extradata[i]);
 		}
@@ -592,6 +575,7 @@ opencalin(void)
 	FILE *fpin;
 
 	/* open up calendar file */
+	cal_file = calendarFile;
 	if ((fpin = fopen(calendarFile, "r")) == NULL) {
 		if (doall) {
 			if (chdir(calendarHomes[0]) != 0)
diff --git a/usr.bin/calendar/tests/Makefile b/usr.bin/calendar/tests/Makefile
index db0c963db1bb..69c2d87a4f6f 100644
--- a/usr.bin/calendar/tests/Makefile
+++ b/usr.bin/calendar/tests/Makefile
@@ -2,10 +2,18 @@
 
 PACKAGE=	tests
 
-TAP_TESTS_SH=	legacy_test
+TAP_TESTS_SH=	comment_test cond_test legacy_test
 
+TEST_METADATA.comment_test+=	timeout="600"
+TEST_METADATA.cond_test+=	timeout="600"
 TEST_METADATA.legacy_test+=	timeout="600"
 
+${PACKAGE}FILES+=		calendar.comment
+${PACKAGE}FILES+=		regress.comment.out
+
+${PACKAGE}FILES+=		calendar.cond
+${PACKAGE}FILES+=		regress.cond.out
+
 ${PACKAGE}FILES+=		calendar.calibrate
 ${PACKAGE}FILES+=		regress.a1.out
 ${PACKAGE}FILES+=		regress.a2.out
diff --git a/usr.bin/calendar/tests/calendar.comment b/usr.bin/calendar/tests/calendar.comment
new file mode 100644
index 000000000000..6af037ec7e9d
--- /dev/null
+++ b/usr.bin/calendar/tests/calendar.comment
@@ -0,0 +1,10 @@
+1 1	jan 1 // comment
+1 2	jan 2 /* comment */
+1 3	jan /* comment */3
+1 4	/* comment*/jan 4
+// comment
+/* comment */1 5	jan 5
+1/* comment */ 6	jan 6
+1 7	jan 7 // /* comment */ comment
+1 1/* comment */1	jan /* comment */11 // comment
+
diff --git a/usr.bin/calendar/tests/calendar.cond b/usr.bin/calendar/tests/calendar.cond
new file mode 100644
index 000000000000..98806e50be67
--- /dev/null
+++ b/usr.bin/calendar/tests/calendar.cond
@@ -0,0 +1,83 @@
+#define DEF1
+
+1 1	jan 1 OK
+
+#ifdef DEF1
+1 2	jan 2 OK
+#endif
+
+1 3	jan 3 OK
+
+#ifdef	DEF2
+1 4	jan 4 NOT OK
+#else
+1 5	jan 5 OK
+#endif
+
+#ifndef	DEF2
+1 6	jan 6 OK
+#else
+1 7	jan 7 NOT OK
+#endif
+
+#ifdef DEF1
+#ifndef DEF2
+1 8	jan 8 OK
+#endif
+#endif
+
+#ifdef DEF1
+#ifdef DEF2
+1 9	jan 9 NOT OK
+#else
+1 10	jan 10 OK
+#endif
+#else
+1 11	jan 11 NOT OK
+#endif
+
+#define DEF2
+
+#ifndef DEF1	// skip = 1
+#ifndef DEF2	// skip = 2
+1 12	jan 12 NOT OK
+#else		// skip = 1 unskip = 0
+1 13	jan 13 NOT OK
+#endif		// skip = 0 unskip = 0
+#else		// skip = 0 unskip = 1
+1 14	jan 14 OK
+#endif		// skip = 0 unskip = 0
+
+#undef DEF1
+
+#ifdef DEF1 // OFF
+#ifdef DEF2 // ON
+#ifdef DEF3 // OFF
+1 15	jan 15 NOT OK
+#else
+1 16	jan 16 NOT OK
+#endif // DEF3
+#else // DEF2
+#ifdef DEF3
+1 17	jan 17 NOT OK
+#else
+1 18	jan 18 NOT OK
+#endif // DEF3
+#endif // DEF2
+#else // DEF1
+#ifdef DEF2
+#ifdef DEF3
+1 19	jan 19 NOT OK
+#else
+1 20	jan 20 OK
+#endif // DEF3
+#else // DEF2
+#ifdef DEF3
+1 21	jan 21 NOT OK
+#else
+1 22	jan 22 NOT OK
+#endif // DEF3
+#endif // DEF2
+#endif // DEF1
+
+1 23	jan 23 OK
\ No newline at end of file
diff --git a/usr.bin/calendar/tests/comment.sh b/usr.bin/calendar/tests/comment.sh
new file mode 100755
index 000000000000..adde5d755252
--- /dev/null
+++ b/usr.bin/calendar/tests/comment.sh
@@ -0,0 +1,14 @@
+# $FreeBSD$
+
+CALENDAR_FILE="-f ${SRCDIR}/calendar.comment"
+CALENDAR_BIN="calendar"
+
+CALENDAR="${CALENDAR_BIN} ${CALENDAR_FILE}"
+
+REGRESSION_START($1)
+
+echo 1..1
+
+REGRESSION_TEST(`comment',`$CALENDAR -t 01.01.2020 -A 30')
+
+REGRESSION_END()
diff --git a/usr.bin/calendar/tests/comment_test.sh b/usr.bin/calendar/tests/comment_test.sh
new file mode 100755
index 000000000000..c44fe63c9aed
--- /dev/null
+++ b/usr.bin/calendar/tests/comment_test.sh
@@ -0,0 +1,6 @@
+#!/bin/sh
+# $FreeBSD$
+
+SRCDIR="$(dirname "${0}")"; export SRCDIR
+
+m4 "${SRCDIR}/../regress.m4" "${SRCDIR}/comment.sh" | sh
diff --git a/usr.bin/calendar/tests/cond.sh b/usr.bin/calendar/tests/cond.sh
new file mode 100755
index 000000000000..420aaf1d7c5c
--- /dev/null
+++ b/usr.bin/calendar/tests/cond.sh
@@ -0,0 +1,14 @@
+# $FreeBSD$
+
+CALENDAR_FILE="-f ${SRCDIR}/calendar.cond"
+CALENDAR_BIN="calendar"
+
+CALENDAR="${CALENDAR_BIN} ${CALENDAR_FILE}"
+
+REGRESSION_START($1)
+
+echo 1..1
+
+REGRESSION_TEST(`cond',`$CALENDAR -t 01.01.2020 -A 30')
+
+REGRESSION_END()
diff --git a/usr.bin/calendar/tests/cond_test.sh b/usr.bin/calendar/tests/cond_test.sh
new file mode 100755
index 000000000000..f00509f3a27c
--- /dev/null
+++ b/usr.bin/calendar/tests/cond_test.sh
@@ -0,0 +1,6 @@
+#!/bin/sh
+# $FreeBSD$
+
+SRCDIR="$(dirname "${0}")"; export SRCDIR
+
+m4 "${SRCDIR}/../regress.m4" "${SRCDIR}/cond.sh" | sh
diff --git a/usr.bin/calendar/tests/regress.comment.out b/usr.bin/calendar/tests/regress.comment.out
new file mode 100644
index 000000000000..1ba3d8cc640e
--- /dev/null
+++ b/usr.bin/calendar/tests/regress.comment.out
@@ -0,0 +1,8 @@
+Jan  1 	jan 1
+Jan  2 	jan 2
+Jan  3 	jan 3
+Jan  4 	jan 4
+Jan  5 	jan 5
+Jan  6 	jan 6
+Jan  7 	jan 7
+Jan 11 	jan 11
diff --git a/usr.bin/calendar/tests/regress.cond.out b/usr.bin/calendar/tests/regress.cond.out
new file mode 100644
index 000000000000..5f5c24829f0c
--- /dev/null
+++ b/usr.bin/calendar/tests/regress.cond.out
@@ -0,0 +1,10 @@
+Jan  1 	jan 1 OK
+Jan  2 	jan 2 OK
+Jan  3 	jan 3 OK
+Jan  5 	jan 5 OK
+Jan  6 	jan 6 OK
+Jan  8 	jan 8 OK
+Jan 10 	jan 10 OK
+Jan 14 	jan 14 OK
+Jan 20 	jan 20 OK
+Jan 23 	jan 23 OK