-                               static int CDC_Host_putchar(char c, FILE* Stream);
-                               static int CDC_Host_getchar(FILE* Stream);
-                               static int CDC_Host_getchar_Blocking(FILE* Stream);
+                               static int CDC_Host_putchar(char c, FILE* Stream) ATTR_NON_NULL_PTR_ARG(2);
+                               static int CDC_Host_getchar(FILE* Stream) ATTR_NON_NULL_PTR_ARG(1);
+                               static int CDC_Host_getchar_Blocking(FILE* Stream) ATTR_NON_NULL_PTR_ARG(1);