-char **strv_env_merge(char **x, ...) _sentinel_;
-char **strv_env_delete(char **x, ...) _sentinel_;
+char **strv_env_merge(unsigned n_lists, ...);
+char **strv_env_delete(char **x, unsigned n_lists, ...);
+
+char **strv_env_set(char **x, const char *p);