diff --git a/rattail_corepos/corepos/importing/db/exporters/catapult_inventory.py b/rattail_corepos/corepos/importing/db/exporters/catapult_inventory.py
index 3965c42..f8a19ea 100644
--- a/rattail_corepos/corepos/importing/db/exporters/catapult_inventory.py
+++ b/rattail_corepos/corepos/importing/db/exporters/catapult_inventory.py
@@ -216,6 +216,12 @@ class InventoryItemImporter(FromCore, catapult_importing.model.InventoryItemImpo
             logger("product %s has no department: %s", product.upc, product)
             return
 
+        size = product.size
+        # 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', '')
+
         price_divider = None
         if (product.quantity and product.group_price and
             product.price_method == corepos_enum.PRODUCT_PRICE_METHOD_ALWAYS):
@@ -374,7 +380,7 @@ class InventoryItemImporter(FromCore, catapult_importing.model.InventoryItemImpo
             'receipt_alias': product.description,
             'brand': product.brand,
             'item_name': product.description,
-            'size': product.size,
+            'size': size,
 
             # TODO: does CORE have this?
             # 'sugg_retail': None,