diff --git a/libc/include/sys/xattr.h b/libc/include/sys/xattr.h
index 39b25b1..070913f 100644
--- a/libc/include/sys/xattr.h
+++ b/libc/include/sys/xattr.h
@@ -35,21 +35,26 @@
 #define XATTR_CREATE 1
 #define XATTR_REPLACE 2
 
-extern int fsetxattr(int fd, const char *name, const void *value, size_t size, int flags);
-extern int setxattr(const char *path, const char *name, const void *value, size_t size, int flags);
-extern int lsetxattr(const char *path, const char *name, const void *value, size_t size, int flags);
+extern int fsetxattr(int fd, const char* name, const void* value, size_t size, int flags)
+  __INTRODUCED_IN(21);
+extern int setxattr(const char* path, const char* name, const void* value, size_t size, int flags)
+  __INTRODUCED_IN(21);
+extern int lsetxattr(const char* path, const char* name, const void* value, size_t size, int flags)
+  __INTRODUCED_IN(21);
 
-extern ssize_t fgetxattr(int fd, const char *name, void *value, size_t size);
-extern ssize_t getxattr(const char *path, const char *name, void *value, size_t size);
-extern ssize_t lgetxattr(const char *path, const char *name, void *value, size_t size);
+extern ssize_t fgetxattr(int fd, const char* name, void* value, size_t size) __INTRODUCED_IN(21);
+extern ssize_t getxattr(const char* path, const char* name, void* value, size_t size)
+  __INTRODUCED_IN(21);
+extern ssize_t lgetxattr(const char* path, const char* name, void* value, size_t size)
+  __INTRODUCED_IN(21);
 
-extern ssize_t listxattr(const char *path, char *list, size_t size);
-extern ssize_t llistxattr(const char *path, char *list, size_t size);
-extern ssize_t flistxattr(int fd, char *list, size_t size);
+extern ssize_t listxattr(const char* path, char* list, size_t size) __INTRODUCED_IN(21);
+extern ssize_t llistxattr(const char* path, char* list, size_t size) __INTRODUCED_IN(21);
+extern ssize_t flistxattr(int fd, char* list, size_t size) __INTRODUCED_IN(21);
 
-extern int removexattr(const char *path, const char *name);
-extern int lremovexattr(const char *path, const char *name);
-extern int fremovexattr(int fd, const char *name);
+extern int removexattr(const char* path, const char* name) __INTRODUCED_IN(21);
+extern int lremovexattr(const char* path, const char* name) __INTRODUCED_IN(21);
+extern int fremovexattr(int fd, const char* name) __INTRODUCED_IN(21);
 
 __END_DECLS