diff --git a/lisp/dired.el b/lisp/dired.el
index 24b128f..f42040d 100644
--- a/lisp/dired.el
+++ b/lisp/dired.el
@@ -3355,8 +3355,8 @@ dired-mark-files-containing-regexp
      (and (not (looking-at-p dired-re-dot))
 	  (not (eolp))			; empty line
 	  (let ((fn (dired-get-filename nil t)))
-	    (when (and fn (file-readable-p fn)
-		       (not (file-directory-p fn)))
+	    (when (and fn (file-regular-p fn)
+		       (file-readable-p fn))
 	      (let ((prebuf (get-file-buffer fn)))
 		(message "Checking %s" fn)
 		;; For now we do it inside emacs
@@ -3364,6 +3364,7 @@ dired-mark-files-containing-regexp
 		(if prebuf
 		    (with-current-buffer prebuf
 		      (save-excursion
+            (revert-buffer t t t)
 			(goto-char (point-min))
 			(re-search-forward regexp nil t)))
 		  (with-temp-buffer