diff --git a/library/src/com/anjlab/android/iab/v3/TransactionDetails.java b/library/src/com/anjlab/android/iab/v3/TransactionDetails.java
index 941ec8ae..6f63d6ba 100644
--- a/library/src/com/anjlab/android/iab/v3/TransactionDetails.java
+++ b/library/src/com/anjlab/android/iab/v3/TransactionDetails.java
@@ -36,7 +36,7 @@ public TransactionDetails(PurchaseInfo info) throws JSONException {
 		JSONObject source = new JSONObject(info.responseData);
 		purchaseInfo = info;
 		productId = source.getString(Constants.RESPONSE_PRODUCT_ID);
-		orderId = source.getString(Constants.RESPONSE_ORDER_ID);
+		orderId = source.optString(Constants.RESPONSE_ORDER_ID);
 		purchaseToken = source.getString(Constants.RESPONSE_PURCHASE_TOKEN);
 		purchaseTime = new Date(source.getLong(Constants.RESPONSE_PURCHASE_TIME));
 	}