diff --git a/peripherals/usart/_v2_ABC_common.yaml b/peripherals/usart/_v2_ABC_common.yaml
index 360e568c3..5ab37af27 100644
--- a/peripherals/usart/_v2_ABC_common.yaml
+++ b/peripherals/usart/_v2_ABC_common.yaml
@@ -144,6 +144,6 @@ ICR:
   PECF:
     Clear: [1, "Clears the PE flag in the ISR register"]
 RDR:
-  RDR: [0, 0xFF]
+  RDR: [0, 0x1FF]
 TDR:
-  TDR: [0, 0xFF]
+  TDR: [0, 0x1FF]