Migrate to Sphinx 1.0 C language constructs.
diff --git a/Doc/library/mailbox.rst b/Doc/library/mailbox.rst
index 7409af5..b041d94 100644
--- a/Doc/library/mailbox.rst
+++ b/Doc/library/mailbox.rst
@@ -452,7 +452,7 @@
                unlock()
 
       Three locking mechanisms are used---dot locking and, if available, the
-      :cfunc:`flock` and :cfunc:`lockf` system calls.
+      :c:func:`flock` and :c:func:`lockf` system calls.
 
 
 .. seealso::
@@ -566,7 +566,7 @@
                unlock()
 
       Three locking mechanisms are used---dot locking and, if available, the
-      :cfunc:`flock` and :cfunc:`lockf` system calls. For MH mailboxes, locking
+      :c:func:`flock` and :c:func:`lockf` system calls. For MH mailboxes, locking
       the mailbox means locking the :file:`.mh_sequences` file and, only for the
       duration of any operations that affect them, locking individual message
       files.
@@ -664,7 +664,7 @@
                unlock()
 
       Three locking mechanisms are used---dot locking and, if available, the
-      :cfunc:`flock` and :cfunc:`lockf` system calls.
+      :c:func:`flock` and :c:func:`lockf` system calls.
 
 
 .. seealso::
@@ -715,7 +715,7 @@
                unlock()
 
       Three locking mechanisms are used---dot locking and, if available, the
-      :cfunc:`flock` and :cfunc:`lockf` system calls.
+      :c:func:`flock` and :c:func:`lockf` system calls.
 
 
 .. seealso::