diff --git a/wp-includes/functions.php b/wp-includes/functions.php
index f64a226ba4..55e732a51d 100644
--- a/wp-includes/functions.php
+++ b/wp-includes/functions.php
@@ -4255,9 +4255,11 @@ function get_main_network_id() {
 		return 1;
 	}
 
+	$current_site = get_current_site();
+
 	if ( defined( 'PRIMARY_NETWORK_ID' ) ) {
 		$main_network_id = PRIMARY_NETWORK_ID;
-	} elseif ( 1 === (int) get_current_site()->id ) {
+	} elseif ( isset( $current_site->id ) && 1 === (int) $current_site->id ) {
 		// If the current network has an ID of 1, assume it is the main network.
 		$main_network_id = 1;
 	} else {
diff --git a/wp-includes/load.php b/wp-includes/load.php
index 9ab44f018f..f474c5c87e 100644
--- a/wp-includes/load.php
+++ b/wp-includes/load.php
@@ -807,6 +807,29 @@ function get_current_blog_id() {
 	return absint($blog_id);
 }
 
+/**
+ * Retrieves the current network ID.
+ *
+ * @since 4.6.0
+ *
+ * @global WP_Network $current_site The current network.
+ *
+ * @return int The ID of the current network.
+ */
+function get_current_network_id() {
+	if ( ! is_multisite() ) {
+		return 1;
+	}
+
+	$current_site = get_current_site();
+
+	if ( ! isset( $current_site->id ) ) {
+		return get_main_network_id();
+	}
+
+	return absint( $current_site->id );
+}
+
 /**
  * Attempt an early load of translations.
  *
diff --git a/wp-includes/version.php b/wp-includes/version.php
index a424090958..969702982f 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.6-alpha-37669';
+$wp_version = '4.6-alpha-37670';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.