diff --git a/src_features/signMessageEIP712/encode_field.c b/src_features/signMessageEIP712/encode_field.c
index a48d0fa..98183b0 100644
--- a/src_features/signMessageEIP712/encode_field.c
+++ b/src_features/signMessageEIP712/encode_field.c
@@ -48,6 +48,7 @@ static void *field_encode(const uint8_t *const value,
                 start_idx = 0;
                 break;
             default:
+                apdu_response_code = APDU_RESPONSE_CONDITION_NOT_SATISFIED;
                 return NULL; // should not be here
         }
         memcpy(&padded_value[start_idx], value, length);