diff --git a/php-project.el b/php-project.el
index c36c81f7..d478d9ec 100644
--- a/php-project.el
+++ b/php-project.el
@@ -95,10 +95,15 @@
       Try to search file in order of `php-project-available-root-files'.
 
 SYMBOL
-      Key of `php-project-available-root-files'.")
+      Key of `php-project-available-root-files'.
+
+STRING
+      A file/directory name of top level marker.
+      If the string is an actual directory path, it is set as the absolute path
+      of the root directory, not the marker.")
   (make-variable-buffer-local 'php-project-root)
   (put 'php-project-root 'safe-local-variable
-       #'(lambda (v) (assq v php-project-available-root-files))))
+       #'(lambda (v) (or (stringp v) (assq v php-project-available-root-files)))))
 
 ;;;###autoload
 (progn
@@ -177,15 +182,17 @@ Typically it is `pear', `drupal', `wordpress', `symfony2' and `psr2'.")
 ;;;###autoload
 (defun php-project-get-root-dir ()
   "Return path to current PHP project."
-  (let ((detect-method
-         (cond
-          ((stringp php-project-root) (list php-project-root))
-          ((eq php-project-root 'auto)
-           (cl-loop for m in php-project-available-root-files
-                    append (cdr m)))
-          (t (cdr-safe (assq php-project-root php-project-available-root-files))))))
-    (cl-loop for m in detect-method
-             thereis (locate-dominating-file default-directory m))))
+  (if (and (stringp php-project-root) (file-directory-p php-project-root))
+      php-project-root
+    (let ((detect-method
+           (cond
+            ((stringp php-project-root) (list php-project-root))
+            ((eq php-project-root 'auto)
+             (cl-loop for m in php-project-available-root-files
+                      append (cdr m)))
+            (t (cdr-safe (assq php-project-root php-project-available-root-files))))))
+      (cl-loop for m in detect-method
+               thereis (locate-dominating-file default-directory m)))))
 
 (provide 'php-project)
 ;;; php-project.el ends here