diff --git a/libc/include/net/if.h b/libc/include/net/if.h
index f261f71..79b4195 100644
--- a/libc/include/net/if.h
+++ b/libc/include/net/if.h
@@ -41,13 +41,13 @@
 
 struct if_nameindex {
   unsigned if_index;
-  char* if_name;
+  char* _Nullable if_name;
 };
 
-char* if_indextoname(unsigned __index, char* __buf);
-unsigned if_nametoindex(const char* __name);
-struct if_nameindex* if_nameindex(void) __INTRODUCED_IN(24);
-void if_freenameindex(struct if_nameindex* __ptr) __INTRODUCED_IN(24);
+char* _Nullable if_indextoname(unsigned __index, char* _Nonnull __buf);
+unsigned if_nametoindex(const char* _Nonnull __name);
+struct if_nameindex* _Nullable if_nameindex(void) __INTRODUCED_IN(24);
+void if_freenameindex(struct if_nameindex* _Nullable __ptr) __INTRODUCED_IN(24);
 
 __END_DECLS