diff --git a/pisa/errors.py b/pisa/errors.py
index 9cb5172..747103b 100644
--- a/pisa/errors.py
+++ b/pisa/errors.py
@@ -6,7 +6,7 @@ APPOINTMENT_WRONG_FIELD_FORMAT = -4
 APPOINTMENT_FIELD_TOO_SMALL = -5
 APPOINTMENT_FIELD_TOO_BIG = -6
 APPOINTMENT_WRONG_FIELD = -7
-APPOINTMENT_INVALID_SIGNATURE = -10
+APPOINTMENT_INVALID_SIGNATURE = -8
 
 # Custom RPC errors
 RPC_TX_REORGED_AFTER_BROADCAST = -98