diff --git a/rattail_corepos/corepos/importing/db/exporters/catapult_inventory.py b/rattail_corepos/corepos/importing/db/exporters/catapult_inventory.py
index f8a19ea..153fa8e 100644
--- a/rattail_corepos/corepos/importing/db/exporters/catapult_inventory.py
+++ b/rattail_corepos/corepos/importing/db/exporters/catapult_inventory.py
@@ -220,7 +220,8 @@ class InventoryItemImporter(FromCore, catapult_importing.model.InventoryItemImpo
         # TODO: this logic may actually be client-specific?  i just happened to
         # find some of these chars in a client DB and needed to avoid them, b/c
         # the openpyxl lib said IllegalCharacterError
-        size = size.replace('\x00', '')
+        if size is not None:
+            size = size.replace('\x00', '')
 
         price_divider = None
         if (product.quantity and product.group_price and