diff --git a/rattail_corepos/importing/corepos/api.py b/rattail_corepos/importing/corepos/api.py
index 98628c7..0956a12 100644
--- a/rattail_corepos/importing/corepos/api.py
+++ b/rattail_corepos/importing/corepos/api.py
@@ -575,7 +575,10 @@ class ProductImporter(FromCOREPOSAPI, corepos_importing.model.ProductImporter):
                 # pseudo-default" vendorItems record
 
                 def sortkey(item):
-                    dt = datetime.datetime.strptime(item['modified'], '%Y-%m-%d %H:%M:%S')
+                    modified = item.get('modified')
+                    if not modified:
+                        return datetime.datetime(1900, 1, 1)
+                    dt = datetime.datetime.strptime(modified, '%Y-%m-%d %H:%M:%S')
                     return dt
 
                 items = sorted(items, key=sortkey, reverse=True)