2 files changed, 3 insertions, 5 deletions
diff --git a/tvix/eval/src/compiler/mod.rs b/tvix/eval/src/compiler/mod.rs
index 68ff3d48a3df..caf326828fd7 100644
--- a/tvix/eval/src/compiler/mod.rs
+++ b/tvix/eval/src/compiler/mod.rs
@@ -1382,7 +1382,9 @@ pub fn compile<'code>(
         c.context_mut().lambda.chunk.codemap = c.codemap.clone();
     }
 
-    c.compile(LocalIdx::ZERO, expr.clone());
+    let root_span = c.span_for(&expr);
+    let root_slot = c.scope_mut().declare_phantom(root_span);
+    c.compile(root_slot, expr.clone());
 
     // The final operation of any top-level Nix program must always be
     // `OpForce`. A thunk should not be returned to the user in an
diff --git a/tvix/eval/src/compiler/scope.rs b/tvix/eval/src/compiler/scope.rs
index d691a1ae7228..eb722a2c6972 100644
--- a/tvix/eval/src/compiler/scope.rs
+++ b/tvix/eval/src/compiler/scope.rs
@@ -128,10 +128,6 @@ pub struct Upvalue {
 #[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd)]
 pub struct LocalIdx(usize);
 
-impl LocalIdx {
-    pub const ZERO: LocalIdx = LocalIdx(0);
-}
-
 /// Represents a scope known during compilation, which can be resolved
 /// directly to stack indices.
 ///