diff --git a/rattail_corepos/importing/model.py b/rattail_corepos/importing/model.py
index 2f31ba0..a2a1f0a 100644
--- a/rattail_corepos/importing/model.py
+++ b/rattail_corepos/importing/model.py
@@ -140,7 +140,10 @@ class ProductImporter(importing.model.ProductImporter):
 
         unit_size = None
         if 'size' in core_data and core_data['size'] is not None:
-            unit_size = decimal.Decimal(core_data['size'])
+            try:
+                unit_size = decimal.Decimal(core_data['size'])
+            except decimal.InvalidOperation:
+                pass
 
         uom_abbrev = core_data.get('unitofmeasure')