diff --git a/lib/wallet.py b/lib/wallet.py
index 6216d783..d109f7d2 100644
--- a/lib/wallet.py
+++ b/lib/wallet.py
@@ -987,6 +987,8 @@ class Abstract_Wallet(object):
                 age = tx_age
         return age > age_limit
 
+    def can_sign(self, tx):
+        pass
 
 class Imported_Wallet(Abstract_Wallet):