diff --git a/zjit/src/ir.rs b/zjit/src/ir.rs
index 28ac98e5ea..673de4fe3e 100644
--- a/zjit/src/ir.rs
+++ b/zjit/src/ir.rs
@@ -140,7 +140,7 @@ impl std::fmt::Display for Function {
                     Insn::IfFalse { val, target } => { write!(f, "IfFalse {val}, {target:?}")?; }
                     Insn::Return { val } => { write!(f, "Return {val}")?; }
                     Insn::Add { v0, v1 } => { write!(f, "Add {v0}, {v1}")?; }
-                    _ => { write!(f, "idk")?; }
+                    insn => { write!(f, "{insn:?}")?; }
                 }
                 writeln!(f, "");
             }