diff --git a/wp-includes/theme.php b/wp-includes/theme.php
index 420a6844e..838bb27cf 100644
--- a/wp-includes/theme.php
+++ b/wp-includes/theme.php
@@ -1286,6 +1286,11 @@ function validate_current_theme() {
 		switch_theme( WP_DEFAULT_THEME, WP_DEFAULT_THEME );
 		return false;
 	}
+	
+	if ( is_child_theme() && ! file_exists( get_stylesheet_directory() . '/style.css' ) ) {
+		switch_theme( WP_DEFAULT_THEME, WP_DEFAULT_THEME );
+		return false;
+	}
 
 	return true;
 }