diff --git a/tex.el b/tex.el
index c6228917..d1069688 100644
--- a/tex.el
+++ b/tex.el
@@ -2423,15 +2423,14 @@ name of master file if it cannot be determined otherwise."
           ;; Otherwise drop it.
           (setq name (TeX-strip-extension name))))
 
-    (let* ((output-dir (and (or (stringp TeX-master)
-                                (buffer-file-name)) ;; otherwise `name' is "<none>"
-                            (TeX-master-output-dir nondirectory
-                                                   (concat name "." TeX-default-extension))))
-           (reg (and output-dir (TeX--clean-extensions-regexp t)))
-           (is-output-ext
-            (and reg (or (string-match-p reg (concat "." extension))
-                         (string= "prv" extension)))))
-      (if is-output-ext
+    (let* ((reg (TeX--clean-extensions-regexp t))
+           (is-output-ext (and reg
+                               (or (string-match-p reg (concat "." extension))
+                                   (string= "prv" extension))))
+           (output-dir (and is-output-ext
+                        (TeX-master-output-dir nondirectory
+                                              (concat name "." TeX-default-extension)))))
+      (if output-dir
           ;; If output extesnion, use output-dir (directory is already removed)
           ;; in TeX-master-output-dir
           (setq name (concat output-dir (file-name-nondirectory name)))
@@ -2535,22 +2534,27 @@ directory is the same as the directory of TeX-master."
   :type 'string)
 
 (defun TeX-master-output-dir (&optional relative-to-master master-file)
-  (with-current-buffer
-      (find-file-noselect (or master-file (TeX-master-file t)) t)
-    (let ((out-dir (and TeX-output-dir
-                        (file-name-as-directory
-                         (abbreviate-file-name
-                          (substitute-in-file-name
-                           (expand-file-name
-                            TeX-output-dir
-                            (file-name-directory buffer-file-name))))))))
-      ;; Make sure the directory exists
-      (when out-dir
-        (unless (file-exists-p out-dir)
-          (make-directory (file-name-as-directory out-dir) t))
-        (if relative-to-master
-            (file-relative-name out-dir)
-          out-dir)))))
+  (let* ((master-file (or master-file (TeX-master-file t)))
+         (master-buffer
+          (or (get-file-buffer master-file)
+              (and (file-exists-p master-file)
+                   (find-file-noselect master-file t)))))
+    (when master-buffer
+      (with-current-buffer master-buffer
+        (let ((out-dir (and TeX-output-dir
+                            (file-name-as-directory
+                             (abbreviate-file-name
+                              (substitute-in-file-name
+                               (expand-file-name
+                                TeX-output-dir
+                                (file-name-directory buffer-file-name))))))))
+          ;; Make sure the directory exists
+          (when out-dir
+            (unless (file-exists-p out-dir)
+              (make-directory (file-name-as-directory out-dir) t))
+            (if relative-to-master
+                (file-relative-name out-dir)
+              out-dir)))))))
 
 (defcustom TeX-style-local "style"
   "Directory containing hand generated TeX information.