killbill-memoizeit

diff --git a/jaxrs/src/main/java/com/ning/billing/jaxrs/json/AccountJson.java b/jaxrs/src/main/java/com/ning/billing/jaxrs/json/AccountJson.java
index ac02a22..ad30cfa 100644
--- a/jaxrs/src/main/java/com/ning/billing/jaxrs/json/AccountJson.java
+++ b/jaxrs/src/main/java/com/ning/billing/jaxrs/json/AccountJson.java
@@ -135,7 +135,11 @@ public class AccountJson extends AccountJsonSimple {
 
             @Override
             public Currency getCurrency() {
-                return Currency.valueOf(currency);
+                if (currency == null) {
+                    return null;
+                } else {
+                    return Currency.valueOf(currency);
+                }
             }
 
             @Override