diff --git a/hw/char/avr_usart.c b/hw/char/avr_usart.c
index 24d26ad7a1..3aff01cd54 100644
--- a/hw/char/avr_usart.c
+++ b/hw/char/avr_usart.c
@@ -86,7 +86,7 @@ static void update_char_mask(AVRUsartState *usart)
         usart->char_mask = 0b11111111;
         break;
     default:
-        assert(0);
+        g_assert_not_reached();
     }
 }