-void __lock(volatile int *);
-void __unlock(volatile int *);
-int __lockfile(FILE *);
-void __unlockfile(FILE *);
+void __lock(volatile int *) ATTR_LIBC_VISIBILITY;
+void __unlock(volatile int *) ATTR_LIBC_VISIBILITY;
+int __lockfile(FILE *) ATTR_LIBC_VISIBILITY;
+void __unlockfile(FILE *) ATTR_LIBC_VISIBILITY;