diff --git a/src/wp-includes/ms-settings.php b/src/wp-includes/ms-settings.php
index 4f9d9e35792b3..b02dc9d161379 100644
--- a/src/wp-includes/ms-settings.php
+++ b/src/wp-includes/ms-settings.php
@@ -99,6 +99,8 @@
 	wp_load_core_site_options( $site_id );
 }
 
+assert( isset( $wpdb ) );
+assert( isset( $table_prefix ) );
 $wpdb->set_prefix( $table_prefix, false ); // $table_prefix can be set in sunrise.php.
 $wpdb->set_blog_id( $current_blog->blog_id, $current_blog->site_id );
 $table_prefix       = $wpdb->get_blog_prefix();
diff --git a/src/wp-settings.php b/src/wp-settings.php
index 023cdccd5ecc9..03c95fbe0a870 100644
--- a/src/wp-settings.php
+++ b/src/wp-settings.php
@@ -100,7 +100,7 @@
 	include WP_CONTENT_DIR . '/advanced-cache.php';
 
 	// Re-initialize any hooks added manually by advanced-cache.php.
-	if ( $wp_filter ) {
+	if ( ! empty( $wp_filter ) ) {
 		$wp_filter = WP_Hook::build_preinitialized_hooks( $wp_filter );
 	}
 }
@@ -141,6 +141,7 @@
  * @global string $table_prefix The database table prefix.
  */
 if ( ! isset( $GLOBALS['table_prefix'] ) ) {
+	assert( isset( $table_prefix ) );
 	$GLOBALS['table_prefix'] = $table_prefix;
 }