diff --git a/compiler/erg_compiler/context/inquire.rs b/compiler/erg_compiler/context/inquire.rs
index f90ff551..b774d32a 100644
--- a/compiler/erg_compiler/context/inquire.rs
+++ b/compiler/erg_compiler/context/inquire.rs
@@ -1381,7 +1381,7 @@ impl Context {
             .super_classes
             .iter()
             .chain(ctx.super_traits.iter())
-            .filter_map(|sup| self.get_nominal_type_ctx(sup));
+            .map(|sup| self.get_nominal_type_ctx(sup).expect("compiler bug: sup not found"));
         Some(vec![ctx].into_iter().chain(sups))
     }