--- a/lib/dirent.in.h
+++ b/lib/dirent.in.h
@@ -26,13 +26,15 @@
 #ifndef _GL_DIRENT_H
 #define _GL_DIRENT_H
 
+/* The definition of GL_LINK_WARNING is copied here.  */
 
-/* Declare overridden functions.  */
 
 #ifdef __cplusplus
 extern "C" {
 #endif
 
+/* Declare overridden functions.  */
+
 #if @REPLACE_FCHDIR@
 # define opendir rpl_opendir
 extern DIR * opendir (const char *);
@@ -40,6 +42,22 @@
 extern int closedir (DIR *);
 #endif
 
+/* Declare GNU extensions.  */
+
+#if @GNULIB_DIRFD@
+# if !@HAVE_DECL_DIRFD@ && !defined dirfd
+/* Return the file descriptor associated with the given directory stream,
+   or -1 if none exists.  */
+extern int dirfd (DIR const *dir);
+# endif
+#elif defined GNULIB_POSIXCHECK
+# undef dirfd
+# define dirfd(d) \
+    (GL_LINK_WARNING ("dirfd is unportable - " \
+                      "use gnulib module dirfd for portability"), \
+     dirfd (d))
+#endif
+
 #ifdef __cplusplus
 }
 #endif