killbill-memoizeit

diff --git a/account/src/main/java/com/ning/billing/account/api/DefaultAccount.java b/account/src/main/java/com/ning/billing/account/api/DefaultAccount.java
index aebc643..72e3516 100644
--- a/account/src/main/java/com/ning/billing/account/api/DefaultAccount.java
+++ b/account/src/main/java/com/ning/billing/account/api/DefaultAccount.java
@@ -127,7 +127,7 @@ public class DefaultAccount extends EntityBase implements Account {
 
     @Override
     public Integer getBillCycleDay() {
-        return billCycleDay;
+        return Objects.firstNonNull(billCycleDay, 0);
     }
 
     @Override