diff --git a/artiq/language/scan.py b/artiq/language/scan.py
index c174f0344..0454ef362 100644
--- a/artiq/language/scan.py
+++ b/artiq/language/scan.py
@@ -32,6 +32,12 @@ __all__ = ["ScanObject",
 
 
 class ScanObject:
+    def __iter__(self):
+        raise NotImplementedError
+
+    def __len__(self):
+        raise NotImplementedError
+
     def describe(self):
         raise NotImplementedError