diff --git a/wp-includes/formatting.php b/wp-includes/formatting.php
index 7c42bbf210..53cfeeae89 100644
--- a/wp-includes/formatting.php
+++ b/wp-includes/formatting.php
@@ -80,8 +80,8 @@ function wptexturize($text) {
 }
 
 function wptexturize_pushpop_element($text, &$stack, $disabled_elements, $opening = '<', $closing = '>') {
-	$o = preg_quote($opening);
-	$c = preg_quote($closing);
+	$o = preg_quote($opening, '/');
+	$c = preg_quote($closing, '/');
 	foreach($disabled_elements as $element) {
 		if (preg_match('/^'.$o.$element.'\b/', $text)) array_push($stack, $element);
 		if (preg_match('/^'.$o.'\/'.$element.$c.'/', $text)) {
diff --git a/wp-includes/functions.php b/wp-includes/functions.php
index 03019a807c..2f77ecd7ef 100644
--- a/wp-includes/functions.php
+++ b/wp-includes/functions.php
@@ -2682,7 +2682,7 @@ function smilies_init() {
 		} else {
 			$wp_smiliessearch .= '|';
 		}
-		$wp_smiliessearch .= preg_quote($rest);
+		$wp_smiliessearch .= preg_quote($rest, '/');
 	}
 
 	$wp_smiliessearch .= ')(?:\s|$)/m';
diff --git a/xmlrpc.php b/xmlrpc.php
index 85d3a4ed84..d8f5fc8a95 100644
--- a/xmlrpc.php
+++ b/xmlrpc.php
@@ -3300,7 +3300,7 @@ class wp_xmlrpc_server extends IXR_Server {
 
 		$p = explode( "\n\n", $linea );
 
-		$preg_target = preg_quote($pagelinkedto);
+		$preg_target = preg_quote($pagelinkedto, '|');
 
 		foreach ( $p as $para ) {
 			if ( strpos($para, $pagelinkedto) !== false ) { // it exists, but is it a link?
@@ -3322,7 +3322,7 @@ class wp_xmlrpc_server extends IXR_Server {
 				$excerpt= str_replace($context[0], $marker, $excerpt); // swap out the link for our marker
 				$excerpt = strip_tags($excerpt, '<wpcontext>');        // strip all tags but our context marker
 				$excerpt = trim($excerpt);
-				$preg_marker = preg_quote($marker);
+				$preg_marker = preg_quote($marker, '|');
 				$excerpt = preg_replace("|.*?\s(.{0,100}$preg_marker.{0,100})\s.*|s", '$1', $excerpt);
 				$excerpt = strip_tags($excerpt); // YES, again, to remove the marker wrapper
 				break;