diff --git a/wp-includes/ms-blogs.php b/wp-includes/ms-blogs.php
index fb9f2befb9..efc678b4fb 100644
--- a/wp-includes/ms-blogs.php
+++ b/wp-includes/ms-blogs.php
@@ -567,6 +567,17 @@ function restore_current_blog() {
 	return true;
 }
 
+/**
+ * Determines if switch_to_blog() is in effect
+ *
+ * @since 3.5.0
+ *
+ * @return bool True if switched, false otherwise.
+ */
+function is_ms_switched() {
+	return $GLOBALS['_wp_switched'];
+}
+
 /**
  * Check if a particular blog is archived.
  *