diff --git a/Disco.Services/Devices/Importing/DeviceImport.cs b/Disco.Services/Devices/Importing/DeviceImport.cs
index e97ea2da..af35bb94 100644
--- a/Disco.Services/Devices/Importing/DeviceImport.cs
+++ b/Disco.Services/Devices/Importing/DeviceImport.cs
@@ -113,7 +113,7 @@ namespace Disco.Services.Devices.Importing
 
                     Device existingDevice = null;
                     if (DeviceSerialNumberImportField.IsDeviceSerialNumberValid(deviceSerialNumber))
-                        existingDevice = cache.Devices.FirstOrDefault(device => device.SerialNumber == deviceSerialNumber);
+                        existingDevice = cache.FindDevice(deviceSerialNumber);
 
                     var fields = columns.Select(h =>
                     {
diff --git a/Disco.Services/Devices/Importing/XlsxDeviceImportDataReader.cs b/Disco.Services/Devices/Importing/XlsxDeviceImportDataReader.cs
index 800f4708..1713eb42 100644
--- a/Disco.Services/Devices/Importing/XlsxDeviceImportDataReader.cs
+++ b/Disco.Services/Devices/Importing/XlsxDeviceImportDataReader.cs
@@ -23,13 +23,13 @@ namespace Disco.Services.Devices.Importing
         {
             context = Context;
             rawData = RawData;
-            currentRowIndex = 0;
-            rowOffset = currentRowIndex = HasHeaderRow ? 2 : 1;
+            currentRowIndex = -1;
+            rowOffset = HasHeaderRow ? 2 : 1;
         }
 
         public void Reset()
         {
-            currentRowIndex = 0;
+            currentRowIndex = -1;
             currentRow = null;
         }