--- a/eric6/Graphics/UMLGraphicsView.py	Sun Apr 11 11:34:32 2021 +0200
+++ b/eric6/Graphics/UMLGraphicsView.py	Sun Apr 11 12:38:16 2021 +0200
@@ -740,9 +740,7 @@
         from .PackageItem import PackageItem
         from .AssociationItem import AssociationItem
         
-        linenum = 0
-        for line in data[1:]:
-            linenum += 1
+        for linenum, line in enumerate(data[1:], start=1):
             if not line.startswith(("item:", "association:")):
                 return False, linenum