diff --git a/wp-includes/functions-formatting.php b/wp-includes/functions-formatting.php
index 5af4df58b9..61cd1b2806 100644
--- a/wp-includes/functions-formatting.php
+++ b/wp-includes/functions-formatting.php
@@ -521,10 +521,11 @@ function format_to_post($content) {
 
 function zeroise($number,$threshold) { // function to add leading zeros when necessary
 	return sprintf('%0'.$threshold.'s', $number);
-	}
+}
 
 
 function backslashit($string) {
+	$string = preg_replace('/^([0-9])/', '\\\\\\\\\1', $string);
 	$string = preg_replace('/([a-z])/i', '\\\\\1', $string);
 	return $string;
 }
diff --git a/wp-includes/functions.php b/wp-includes/functions.php
index a5f131d1e3..17fcfbd103 100644
--- a/wp-includes/functions.php
+++ b/wp-includes/functions.php
@@ -30,12 +30,12 @@ function mysql2date($dateformatstring, $mysqlstring, $translate = true) {
 		$datemeridiem = $wp_locale->get_meridiem(date('a', $i));
 		$datemeridiem_capital = $wp_locale->get_meridiem(date('A', $i));
 		$dateformatstring = ' '.$dateformatstring;
-		$dateformatstring = preg_replace("/([^\\\])D/", "\${1}".backslashit($dateweekday_abbrev), $dateformatstring);
-		$dateformatstring = preg_replace("/([^\\\])F/", "\${1}".backslashit($datemonth), $dateformatstring);
-		$dateformatstring = preg_replace("/([^\\\])l/", "\${1}".backslashit($dateweekday), $dateformatstring);
-		$dateformatstring = preg_replace("/([^\\\])M/", "\${1}".backslashit($datemonth_abbrev), $dateformatstring);
-		$dateformatstring = preg_replace("/([^\\\])a/", "\${1}".backslashit($datemeridiem), $dateformatstring);
-		$dateformatstring = preg_replace("/([^\\\])A/", "\${1}".backslashit($datemeridiem_capital), $dateformatstring);
+		$dateformatstring = preg_replace("/([^\\\])D/", "\\1".backslashit($dateweekday_abbrev), $dateformatstring);
+		$dateformatstring = preg_replace("/([^\\\])F/", "\\1".backslashit($datemonth), $dateformatstring);
+		$dateformatstring = preg_replace("/([^\\\])l/", "\\1".backslashit($dateweekday), $dateformatstring);
+		$dateformatstring = preg_replace("/([^\\\])M/", "\\1".backslashit($datemonth_abbrev), $dateformatstring);
+		$dateformatstring = preg_replace("/([^\\\])a/", "\\1".backslashit($datemeridiem), $dateformatstring);
+		$dateformatstring = preg_replace("/([^\\\])A/", "\\1".backslashit($datemeridiem_capital), $dateformatstring);
 
 		$dateformatstring = substr($dateformatstring, 1, strlen($dateformatstring)-1);
 	}
@@ -73,12 +73,12 @@ function date_i18n($dateformatstring, $unixtimestamp) {
 		$datemeridiem = $wp_locale->get_meridiem(date('a', $i));
 		$datemeridiem_capital = $wp_locale->get_meridiem(date('A', $i));
 		$dateformatstring = ' '.$dateformatstring;
-		$dateformatstring = preg_replace("/([^\\\])D/", "\${1}".backslashit($dateweekday_abbrev), $dateformatstring);
-		$dateformatstring = preg_replace("/([^\\\])F/", "\${1}".backslashit($datemonth), $dateformatstring);
-		$dateformatstring = preg_replace("/([^\\\])l/", "\${1}".backslashit($dateweekday), $dateformatstring);
-		$dateformatstring = preg_replace("/([^\\\])M/", "\${1}".backslashit($datemonth_abbrev), $dateformatstring);
-		$dateformatstring = preg_replace("/([^\\\])a/", "\${1}".backslashit($datemeridiem), $dateformatstring);
-		$dateformatstring = preg_replace("/([^\\\])A/", "\${1}".backslashit($datemeridiem_capital), $dateformatstring);
+		$dateformatstring = preg_replace("/([^\\\])D/", "\\1".backslashit($dateweekday_abbrev), $dateformatstring);
+		$dateformatstring = preg_replace("/([^\\\])F/", "\\1".backslashit($datemonth), $dateformatstring);
+		$dateformatstring = preg_replace("/([^\\\])l/", "\\1".backslashit($dateweekday), $dateformatstring);
+		$dateformatstring = preg_replace("/([^\\\])M/", "\\1".backslashit($datemonth_abbrev), $dateformatstring);
+		$dateformatstring = preg_replace("/([^\\\])a/", "\\1".backslashit($datemeridiem), $dateformatstring);
+		$dateformatstring = preg_replace("/([^\\\])A/", "\\1".backslashit($datemeridiem_capital), $dateformatstring);
 
 		$dateformatstring = substr($dateformatstring, 1, strlen($dateformatstring)-1);
 	}