diff --git a/coreir/context.py b/coreir/context.py
index 945bbbc..f8a556d 100644
--- a/coreir/context.py
+++ b/coreir/context.py
@@ -48,6 +48,8 @@ def __getitem__(self, key):
 
 def namespace_cache(f):
     def method(self, name: str):
+        if self.context is None:
+            raise ValueError("Cannot use deleted context!")
         c_addr = ct.addressof(self.context)
         if name in _library_cache[c_addr]:
             return _library_cache[c_addr][name]