diff --git a/rattail_corepos/importing/corepos/api.py b/rattail_corepos/importing/corepos/api.py
index 137b90e..20f67b5 100644
--- a/rattail_corepos/importing/corepos/api.py
+++ b/rattail_corepos/importing/corepos/api.py
@@ -509,7 +509,7 @@ class ProductImporter(FromCOREPOSAPI, corepos_importing.model.ProductImporter):
 
         department_number = None
         if 'department' in product:
-            department_number = int(product['department'])
+            department_number = int(product['department']) or None
 
         subdepartment_number = None
         if 'subdept' in product: