diff --git a/NEWS b/NEWS
index 1d3da3086ef..b1540e5adfa 100644
--- a/NEWS
+++ b/NEWS
@@ -6,6 +6,7 @@ PHP                                                                        NEWS
   . Fixed GH-16240: jdtounix overflow on argument value. (David Carlier)
   . Fixed GH-16241: easter_days/easter_date overflow on year argument.
     (David Carlier)
+  . Fixed GH-16263: jddayofweek overflow. (cmb)
 
 - CLI:
   . Fixed bug GH-16137: duplicate http headers when set several times by
diff --git a/ext/calendar/dow.c b/ext/calendar/dow.c
index 38da7e157c2..079dd6c15ad 100644
--- a/ext/calendar/dow.c
+++ b/ext/calendar/dow.c
@@ -33,14 +33,7 @@
 int DayOfWeek(
 				 zend_long sdn)
 {
-	int dow;
-
-	dow = (sdn + 1) % 7;
-	if (dow >= 0) {
-		return (dow);
-	} else {
-		return (dow + 7);
-	}
+	return (int)(sdn % 7 + 8) % 7;
 }
 
 const char * const DayNameShort[7] =
diff --git a/ext/calendar/tests/gh16258.phpt b/ext/calendar/tests/gh16258.phpt
new file mode 100644
index 00000000000..9f2b70fac54
--- /dev/null
+++ b/ext/calendar/tests/gh16258.phpt
@@ -0,0 +1,12 @@
+--TEST--
+GH-16258 (jddayofweek overflow on argument)
+--EXTENSIONS--
+calendar
+--FILE--
+<?php
+jddayofweek(PHP_INT_MAX, 1);
+jddayofweek(PHP_INT_MIN, 1);
+echo "DONE";
+?>
+--EXPECT--
+DONE