diff --git a/ablescript/src/variables.rs b/ablescript/src/variables.rs
index cebd102..e9dec5b 100644
--- a/ablescript/src/variables.rs
+++ b/ablescript/src/variables.rs
@@ -932,7 +932,7 @@ impl Display for Value {
                         body,
                     )
                 }
-                Functio::Builtin(_) => todo!(),
+                Functio::Builtin(b) => write!(f, "builtin @ {}", b.fn_addr()),
                 Functio::Chain { functios, kind } => {
                     let (a, b) = *functios.clone();
                     write!(