diff --git a/loopy/transform/save.py b/loopy/transform/save.py
index 65649a4cc0e3067cdb13646b2f40bbefc414ce07..bc8981281a94bde2685be2efa659b8db01b493bb 100644
--- a/loopy/transform/save.py
+++ b/loopy/transform/save.py
@@ -252,6 +252,7 @@ class TemporarySaver(object):
         if temporary.initializer is not None:
             # Temporaries with initializers do not need saving/reloading - the
             # code generation takes care of emitting the initializers.
+            assert temporary.read_only
             return None
 
         if temporary.base_storage is not None: