diff --git a/lisp/dired.el b/lisp/dired.el
index 6c7445c..057e533 100644
--- a/lisp/dired.el
+++ b/lisp/dired.el
@@ -3215,20 +3215,29 @@ dired-file-marker
 	       (following-char))))))
 
 (defun dired-mark-files-in-region (start end)
+  "Mark all files inside the region in the Dired buffer.
+The mark MARK of a file already marked only changes if:
+1) MARK equals to `dired-del-marker'.
+2) `dired-marked-char' equals to `?\\s' or `dired-del-marker'."
+
   (let ((inhibit-read-only t))
     (if (> start end)
-	(error "start > end"))
-    (goto-char start)			; assumed at beginning of line
+    (error "start > end"))
+    (goto-char start)           ; assumed at beginning of line
     (while (< (point) end)
       ;; Skip subdir line and following garbage like the `total' line:
       (while (and (< (point) end) (dired-between-files))
-	(forward-line 1))
-      (if (and (not (looking-at-p dired-re-dot))
-	       (dired-get-filename nil t))
-	  (progn
-	    (delete-char 1)
-	    (insert dired-marker-char)))
-      (forward-line 1))))
+    (forward-line 1))
+      (when (and (not (looking-at-p dired-re-dot))
+                 (or (looking-at-p "^ ")
+                     (looking-at-p (concat "^" (regexp-quote (char-to-string dired-del-marker))))
+                     (eq dired-marker-char ?\s)
+                     (eq dired-marker-char dired-del-marker))
+                 (dired-get-filename nil t))
+        (delete-char 1)
+        (insert dired-marker-char))
+      (forward-line 1))
+    (deactivate-mark 'force)))
 
 (defun dired-mark (arg &optional interactive)
   "Mark the file at point in the Dired buffer.
@@ -3237,6 +3246,10 @@ dired-mark
 
 If on a subdir headerline, mark all its files except `.' and `..'.
 
+The mark MARK of a file already marked only changes if:
+1) MARK equals to `dired-del-marker'.
+2) `dired-marked-char' equals to `?\\s' or `dired-del-marker'.
+
 Use \\[dired-unmark-all-files] to remove all marks
 and \\[dired-unmark] on a subdir to remove the marks in
 this subdir."
@@ -3246,10 +3259,10 @@ dired-mark
    ((and interactive (use-region-p))
     (save-excursion
       (let ((beg (region-beginning))
-	    (end (region-end)))
-	(dired-mark-files-in-region
-	 (progn (goto-char beg) (line-beginning-position))
-	 (progn (goto-char end) (line-beginning-position))))))
+        (end (region-end)))
+    (dired-mark-files-in-region
+     (progn (goto-char beg) (line-beginning-position))
+     (progn (goto-char end) (line-beginning-position))))))
    ;; Mark subdir files from the subdir headerline.
    ((dired-get-subdir)
     (save-excursion (dired-mark-subdir-files)))
@@ -3258,7 +3271,11 @@ dired-mark
     (let ((inhibit-read-only t))
       (dired-repeat-over-lines
        (prefix-numeric-value arg)
-       (function (lambda () (delete-char 1) (insert dired-marker-char))))))))
+       (function (lambda () (when (or (looking-at-p "^ ")
+                                      (looking-at-p (concat "^" (regexp-quote (char-to-string dired-del-marker))))
+                                      (eq dired-marker-char ?\s)
+                                      (eq dired-marker-char dired-del-marker))
+                              (delete-char 1) (insert dired-marker-char)))))))))
 
 (defun dired-unmark (arg &optional interactive)
   "Unmark the file at point in the Dired buffer.