diff --git a/libc/include/arpa/inet.h b/libc/include/arpa/inet.h
index db054c9..748b7a1 100644
--- a/libc/include/arpa/inet.h
+++ b/libc/include/arpa/inet.h
@@ -36,17 +36,17 @@
 
 __BEGIN_DECLS
 
-in_addr_t inet_addr(const char* __s);
-int inet_aton(const char* __s, struct in_addr* __addr);
+in_addr_t inet_addr(const char* _Nonnull __s);
+int inet_aton(const char* _Nonnull __s, struct in_addr* _Nullable __addr);
 in_addr_t inet_lnaof(struct in_addr __addr) __INTRODUCED_IN(21);
 struct in_addr inet_makeaddr(in_addr_t __net, in_addr_t __host) __INTRODUCED_IN(21);
 in_addr_t inet_netof(struct in_addr __addr) __INTRODUCED_IN(21);
-in_addr_t inet_network(const char* __s) __INTRODUCED_IN(21);
-char* inet_ntoa(struct in_addr __addr);
-const char* inet_ntop(int __af, const void* __src, char* __dst, socklen_t __size);
-unsigned int inet_nsap_addr(const char* __ascii, unsigned char* __binary, int __n);
-char* inet_nsap_ntoa(int __binary_length, const unsigned char* __binary, char* __ascii);
-int inet_pton(int __af, const char* __src, void* __dst);
+in_addr_t inet_network(const char* _Nonnull __s) __INTRODUCED_IN(21);
+char* _Nonnull inet_ntoa(struct in_addr __addr);
+const char* _Nullable inet_ntop(int __af, const void* _Nonnull __src, char* _Nonnull __dst, socklen_t __size);
+unsigned int inet_nsap_addr(const char* _Nonnull __ascii, unsigned char* _Nonnull __binary, int __n);
+char* _Nonnull inet_nsap_ntoa(int __binary_length, const unsigned char* _Nonnull __binary, char* _Nullable __ascii);
+int inet_pton(int __af, const char* _Nonnull __src, void* _Nonnull __dst);
 
 __END_DECLS