diff --git a/include/unistd.h b/include/unistd.h
index 203a4608d5..a382d303bb 100644
--- a/include/unistd.h
+++ b/include/unistd.h
@@ -32,7 +32,7 @@ extern int __lchown (__const char *__file, __uid_t __owner,
 extern int __chdir (__const char *__path);
 extern int __fchdir (int __fd);
 extern char *__getcwd (char *__buf, size_t __size);
-extern int __mkdir (const char *__path, mode_t __mode);
+extern int __mkdir (const char *__path, __mode_t __mode);
 extern int __rmdir (const char *__path);
 
 /* Get the canonical absolute name of the named directory, and put it in SIZE