killbill-aplcache

diff --git a/invoice/src/main/java/com/ning/billing/invoice/api/user/DefaultInvoiceUserApi.java b/invoice/src/main/java/com/ning/billing/invoice/api/user/DefaultInvoiceUserApi.java
index 9bd830e..3bf9846 100644
--- a/invoice/src/main/java/com/ning/billing/invoice/api/user/DefaultInvoiceUserApi.java
+++ b/invoice/src/main/java/com/ning/billing/invoice/api/user/DefaultInvoiceUserApi.java
@@ -58,7 +58,8 @@ public class DefaultInvoiceUserApi implements InvoiceUserApi {
 
 	@Override
 	public BigDecimal getAccountBalance(UUID accountId) {
-		return dao.getAccountBalance(accountId);
+		BigDecimal result = dao.getAccountBalance(accountId);
+		return result == null ? BigDecimal.ZERO : result;
 	}
 
 }