diff --git a/ext/calendar/gregor.c b/ext/calendar/gregor.c
index f48950901a6..c9c0bf761b4 100644
--- a/ext/calendar/gregor.c
+++ b/ext/calendar/gregor.c
@@ -154,6 +154,13 @@ void SdnToGregorian(
 	}
 	temp = (sdn + GREGOR_SDN_OFFSET) * 4 - 1;
 
+	if (temp < 0) {
+		*pYear = 0;
+		*pMonth = 0;
+		*pDay = 0;
+		return;
+	}
+
 	/* Calculate the century (year/100). */
 	century = temp / DAYS_PER_400_YEARS;
 
diff --git a/ext/calendar/tests/cal_info.phpt b/ext/calendar/tests/cal_info.phpt
index ae57a87724a..2e3e612925c 100644
--- a/ext/calendar/tests/cal_info.phpt
+++ b/ext/calendar/tests/cal_info.phpt
@@ -1,5 +1,7 @@
 --TEST--
 cal_info()
+--INI--
+date.timezone=UTC
 --SKIPIF--
 <?php include 'skipif.inc'; ?>
 --FILE--
@@ -8,7 +10,7 @@ cal_info()
   print_r(cal_info(1));
   print_r(cal_info(99999));
 ?>
---EXPECT--
+--EXPECTF--
 Array
 (
     [0] => Array
@@ -211,4 +213,4 @@ Array
     [calsymbol] => CAL_JULIAN
 )
 
-Warning: cal_info(): invalid calendar ID 99999. in /home/hartmut/projects/php/dev/head/ext/calendar/tests/cal_info.php on line 4
+Warning: cal_info(): invalid calendar ID 99999. in %s on line %d
diff --git a/ext/calendar/tests/easter_date.phpt b/ext/calendar/tests/easter_date.phpt
index ab00e40c7db..55a3670dad2 100644
--- a/ext/calendar/tests/easter_date.phpt
+++ b/ext/calendar/tests/easter_date.phpt
@@ -1,5 +1,7 @@
 --TEST--
 easter_date()
+--INI--
+date.timezone=UTC
 --SKIPIF--
 <?php include 'skipif.inc'; ?>
 --FILE--
@@ -10,9 +12,9 @@ echo date("Y-m-d", easter_date(2002))."\n";
 echo date("Y-m-d", easter_date(1492))."\n";
 ?>
 --EXPECTF--
-2000-04-23
-2001-04-15
-2002-03-31
+2000-04-22
+2001-04-14
+2002-03-30
 
-Warning: easter_date(): This function is only valid for years between 1970 and 2037 inclusive in %seaster_date.php on line 5
+Warning: easter_date(): This function is only valid for years between 1970 and 2037 inclusive in %s on line %d
 1970-01-01
diff --git a/ext/calendar/tests/jdtomonthname.phpt b/ext/calendar/tests/jdtomonthname.phpt
new file mode 100644
index 00000000000..1b5118a96f6
--- /dev/null
+++ b/ext/calendar/tests/jdtomonthname.phpt
@@ -0,0 +1,71 @@
+--TEST--
+jdtomonthname() test
+--SKIPIF--
+<?php if (!extension_loaded("calendar")) print "skip"; ?>
+--FILE--
+<?php
+
+$jd_days = Array(
+    2453396,
+    2440588,
+    -1,
+    array(),
+    1000000000
+    );
+
+foreach ($jd_days as $jd_day) {
+    var_dump(jdmonthname($jd_day,0));
+    var_dump(jdmonthname($jd_day,1));
+    var_dump(jdmonthname($jd_day,2));
+    var_dump(jdmonthname($jd_day,3));
+    var_dump(jdmonthname($jd_day,4));
+    var_dump(jdmonthname($jd_day,5));
+}
+
+echo "Done\n";
+
+?>
+--EXPECTF--	
+string(3) "Jan"
+string(7) "January"
+string(3) "Jan"
+string(7) "January"
+string(6) "Shevat"
+string(0) ""
+string(3) "Jan"
+string(7) "January"
+string(3) "Dec"
+string(8) "December"
+string(5) "Tevet"
+string(0) ""
+string(0) ""
+string(0) ""
+string(0) ""
+string(0) ""
+string(0) ""
+string(0) ""
+
+Warning: jdmonthname() expects parameter 1 to be long, array given in %s on line %d
+bool(false)
+
+Warning: jdmonthname() expects parameter 1 to be long, array given in %s on line %d
+bool(false)
+
+Warning: jdmonthname() expects parameter 1 to be long, array given in %s on line %d
+bool(false)
+
+Warning: jdmonthname() expects parameter 1 to be long, array given in %s on line %d
+bool(false)
+
+Warning: jdmonthname() expects parameter 1 to be long, array given in %s on line %d
+bool(false)
+
+Warning: jdmonthname() expects parameter 1 to be long, array given in %s on line %d
+bool(false)
+string(0) ""
+string(0) ""
+string(0) ""
+string(0) ""
+string(6) "AdarII"
+string(0) ""
+Done
diff --git a/ext/calendar/tests/jdtounix.phpt b/ext/calendar/tests/jdtounix.phpt
index 055f7fe117f..8d855433003 100644
--- a/ext/calendar/tests/jdtounix.phpt
+++ b/ext/calendar/tests/jdtounix.phpt
@@ -1,5 +1,7 @@
 --TEST--
 jdtounix()
+--INI--
+date.timezone=UTC
 --SKIPIF--
 <?php include 'skipif.inc'; ?>
 --FILE--