diff --git a/crates/erg_compiler/ty/mod.rs b/crates/erg_compiler/ty/mod.rs
index a9bec0a6..f2e6b922 100644
--- a/crates/erg_compiler/ty/mod.rs
+++ b/crates/erg_compiler/ty/mod.rs
@@ -1956,6 +1956,7 @@ impl HasType for Type {
 
 impl HasLevel for Type {
     fn level(&self) -> Option<usize> {
+        println!("lev: {self}");
         match self {
             Self::FreeVar(v) => v.level(),
             Self::Ref(t) => t.level(),
@@ -2034,7 +2035,10 @@ impl HasLevel for Type {
                     Some(min)
                 }
             }
-            Self::Structural(ty) => ty.level(),
+            Self::Structural(ty) => {
+                set_recursion_limit!(None, 128);
+                ty.level()
+            }
             Self::Guard(guard) => guard.to.level(),
             Self::Quantified(quant) => quant.level(),
             Self::Bounded { sub, sup } => {