diff --git a/XeroNetStandardApp/Controllers/Accounting/InvoiceSyncController.cs b/XeroNetStandardApp/Controllers/Accounting/InvoiceSyncController.cs
index e4731c5..92f2e9c 100644
--- a/XeroNetStandardApp/Controllers/Accounting/InvoiceSyncController.cs
+++ b/XeroNetStandardApp/Controllers/Accounting/InvoiceSyncController.cs
@@ -102,8 +102,8 @@ public async Task<IActionResult> Upload(List<IFormFile> files, Guid invoiceId)
                         byteArray = ms.ToArray();
                     }
 
-                    // Call attach file to invoice endpoint
-                    await Api.CreateInvoiceAttachmentByFileNameAsync(XeroToken.AccessToken, TenantId, invoiceId, formFile.FileName, byteArray);
+                    using var stream = new MemoryStream(byteArray);
+                    await Api.CreateInvoiceAttachmentByFileNameAsync(XeroToken.AccessToken, TenantId, invoiceId, formFile.FileName, stream);
                 }
             }
 
diff --git a/XeroNetStandardApp/Controllers/Accounting/PurchaseOrderSyncController.cs b/XeroNetStandardApp/Controllers/Accounting/PurchaseOrderSyncController.cs
index 537b43d..74c8ebf 100644
--- a/XeroNetStandardApp/Controllers/Accounting/PurchaseOrderSyncController.cs
+++ b/XeroNetStandardApp/Controllers/Accounting/PurchaseOrderSyncController.cs
@@ -125,7 +125,8 @@ public async Task<IActionResult> Upload(List<IFormFile> files, string purchaseOr
                         byteArray = ms.ToArray();
                     }
 
-                    await Api.CreatePurchaseOrderAttachmentByFileNameAsync(XeroToken.AccessToken, TenantId, Guid.Parse(purchaseOrderId), formFile.FileName, byteArray);
+                    using var stream = new MemoryStream(byteArray);
+                    await Api.CreatePurchaseOrderAttachmentByFileNameAsync(XeroToken.AccessToken, TenantId, Guid.Parse(purchaseOrderId), formFile.FileName, stream);       
                 }
             }