diff --git a/wp-includes/class-wp-theme.php b/wp-includes/class-wp-theme.php
index d86f74fb0..37b73f2cc 100644
--- a/wp-includes/class-wp-theme.php
+++ b/wp-includes/class-wp-theme.php
@@ -292,6 +292,9 @@ final class WP_Theme implements ArrayAccess {
 				return $this->get_theme_root();
 			case 'theme_root_uri' :
 				return $this->get_theme_root_uri();
+			// For cases where the array was converted to an object.
+			default :
+				return $this->offsetGet( $offset );
 		}
 	}