diff --git a/ext/date/lib/dow.c b/ext/date/lib/dow.c
index 52f43b1a89d..c288e5db972 100644
--- a/ext/date/lib/dow.c
+++ b/ext/date/lib/dow.c
@@ -52,7 +52,7 @@ static timelib_sll timelib_day_of_week_ex(timelib_sll y, timelib_sll m, timelib_
 	/* Only valid for Gregorian calendar, commented out as we don't handle
 	 * Julian calendar. We just return the 'wrong' day of week to be
 	 * consistent. */
-	c1 = century_value(y / 100);
+	c1 = century_value(positive_mod(y, 400) / 100);
 	y1 = positive_mod(y, 100);
 	m1 = timelib_is_leap(y) ? m_table_leap[m] : m_table_common[m];
 	dow = positive_mod((c1 + y1 + m1 + (y1 / 4) + d), 7);
diff --git a/ext/date/tests/bug49585.phpt b/ext/date/tests/bug49585.phpt
index d21bba6c5ce..c078618b3d9 100644
--- a/ext/date/tests/bug49585.phpt
+++ b/ext/date/tests/bug49585.phpt
@@ -13,5 +13,5 @@ var_dump($date->format('c'));
 ?>
 --EXPECT--
 string(32) "Fri, 01 Jan -1500 00:00:00 +0000"
-string(38) "Mon, 01 Jan -2147483648 00:00:00 +0000"
+string(38) "Tue, 01 Jan -2147483648 00:00:00 +0000"
 string(32) "-2147483648-01-01T00:00:00+00:00"
diff --git a/ext/date/tests/bug75851.phpt b/ext/date/tests/bug75851.phpt
index d447792b931..0427e09885c 100644
--- a/ext/date/tests/bug75851.phpt
+++ b/ext/date/tests/bug75851.phpt
@@ -13,9 +13,9 @@ echo date(DATE_ATOM."\n".DATE_RFC2822."\nc\nr\no\ny\nY\nU\n\n", PHP_INT_MAX);
 ?>
 --EXPECT--
 -292277022657-01-27T08:29:52+00:00
-Fri, 27 Jan -292277022657 08:29:52 +0000
+Sun, 27 Jan -292277022657 08:29:52 +0000
 -292277022657-01-27T08:29:52+00:00
-Fri, 27 Jan -292277022657 08:29:52 +0000
+Sun, 27 Jan -292277022657 08:29:52 +0000
 -292277022657
 -57
 -292277022657
diff --git a/ext/date/tests/bug77243-001.phpt b/ext/date/tests/bug77243-001.phpt
new file mode 100644
index 00000000000..e52b4530716
--- /dev/null
+++ b/ext/date/tests/bug77243-001.phpt
@@ -0,0 +1,34 @@
+--TEST--
+Bug #77243 (Weekdays are calculated incorrectly for negative years)
+--FILE--
+<?php
+date_default_timezone_set('UTC');
+
+$time=-62167046400; // 0000-01-03 0-01-1
+
+for ($i = -10; $i < 10; $i++ )
+{
+	echo date('Y-m-d o-W-N', $time + ($i * 86400)), "\n";
+}
+?>
+--EXPECT--
+-0001-12-24 -1-51-5
+-0001-12-25 -1-51-6
+-0001-12-26 -1-51-7
+-0001-12-27 -1-52-1
+-0001-12-28 -1-52-2
+-0001-12-29 -1-52-3
+-0001-12-30 -1-52-4
+-0001-12-31 -1-52-5
+0000-01-01 -1-52-6
+0000-01-02 -1-52-7
+0000-01-03 0-01-1
+0000-01-04 0-01-2
+0000-01-05 0-01-3
+0000-01-06 0-01-4
+0000-01-07 0-01-5
+0000-01-08 0-01-6
+0000-01-09 0-01-7
+0000-01-10 0-02-1
+0000-01-11 0-02-2
+0000-01-12 0-02-3
diff --git a/ext/date/tests/bug77243-002.phpt b/ext/date/tests/bug77243-002.phpt
new file mode 100644
index 00000000000..40ea576aae3
--- /dev/null
+++ b/ext/date/tests/bug77243-002.phpt
@@ -0,0 +1,68 @@
+--TEST--
+Bug #77243 (Weekdays are calculated incorrectly for negative years)
+--FILE--
+<?php
+date_default_timezone_set('UTC');
+
+$startingPoints = [
+	-62167046400 - (((101 * 365) + 25) * 86400),
+	-62167046400 - (((100 * 365) + 25) * 86400),
+	-62167046400 - ((( 99 * 365) + 25) * 86400),
+];
+
+foreach ($startingPoints as $startingPoint)
+{
+	for ($i = -7; $i < 7; $i++ )
+	{
+		echo date('Y-m-d o-W-N', $startingPoint + ($i * 86400)), "\n";
+	}
+	echo "\n\n";
+}
+?>
+--EXPECT--
+-0102-12-26 -102-52-1
+-0102-12-27 -102-52-2
+-0102-12-28 -102-52-3
+-0102-12-29 -102-52-4
+-0102-12-30 -102-52-5
+-0102-12-31 -102-52-6
+-0101-01-01 -102-52-7
+-0101-01-02 -101-01-1
+-0101-01-03 -101-01-2
+-0101-01-04 -101-01-3
+-0101-01-05 -101-01-4
+-0101-01-06 -101-01-5
+-0101-01-07 -101-01-6
+-0101-01-08 -101-01-7
+
+
+-0101-12-26 -101-52-2
+-0101-12-27 -101-52-3
+-0101-12-28 -101-52-4
+-0101-12-29 -101-52-5
+-0101-12-30 -101-52-6
+-0101-12-31 -101-52-7
+-0100-01-01 -100-01-1
+-0100-01-02 -100-01-2
+-0100-01-03 -100-01-3
+-0100-01-04 -100-01-4
+-0100-01-05 -100-01-5
+-0100-01-06 -100-01-6
+-0100-01-07 -100-01-7
+-0100-01-08 -100-02-1
+
+
+-0100-12-26 -100-52-3
+-0100-12-27 -100-52-4
+-0100-12-28 -100-52-5
+-0100-12-29 -100-52-6
+-0100-12-30 -100-52-7
+-0100-12-31 -99-01-1
+-0099-01-01 -99-01-2
+-0099-01-02 -99-01-3
+-0099-01-03 -99-01-4
+-0099-01-04 -99-01-5
+-0099-01-05 -99-01-6
+-0099-01-06 -99-01-7
+-0099-01-07 -99-02-1
+-0099-01-08 -99-02-2