diff --git a/compiler/cl-interpret/src/env.rs b/compiler/cl-interpret/src/env.rs
index 6852989..7276a15 100644
--- a/compiler/cl-interpret/src/env.rs
+++ b/compiler/cl-interpret/src/env.rs
@@ -134,6 +134,18 @@ impl Environment {
         }
         Err(Error::NotDefined(id))
     }
+
+    pub(crate) fn get_local(&self, id: Sym) -> IResult<ConValue> {
+        for (frame, _) in self.frames.iter().rev() {
+            match frame.get(&id) {
+                Some(Some(var)) => return Ok(var.clone()),
+                Some(None) => return Err(Error::NotInitialized(id)),
+                _ => (),
+            }
+        }
+        Err(Error::NotInitialized(id))
+    }
+    
     /// Inserts a new [ConValue] into this [Environment]
     pub fn insert(&mut self, id: Sym, value: Option<ConValue>) {
         if let Some((frame, _)) = self.frames.last_mut() {
diff --git a/compiler/cl-interpret/src/function.rs b/compiler/cl-interpret/src/function.rs
index df3491d..ea771bb 100644
--- a/compiler/cl-interpret/src/function.rs
+++ b/compiler/cl-interpret/src/function.rs
@@ -34,7 +34,7 @@ impl Function {
     pub fn upvars(&self) -> Ref<Upvars> {
         self.upvars.borrow()
     }
-    pub fn lift_upvars(&self, env: &mut Environment) {
+    pub fn lift_upvars(&self, env: &Environment) {
         let upvars = collect_upvars(&self.decl, env);
         if let Ok(mut self_upvars) = self.upvars.try_borrow_mut() {
             *self_upvars = upvars;
diff --git a/compiler/cl-interpret/src/function/collect_upvars.rs b/compiler/cl-interpret/src/function/collect_upvars.rs
index 69e4ccd..236a5fc 100644
--- a/compiler/cl-interpret/src/function/collect_upvars.rs
+++ b/compiler/cl-interpret/src/function/collect_upvars.rs
@@ -28,7 +28,7 @@ impl<'env> CollectUpvars<'env> {
         if blacklist.contains(name) || upvars.contains_key(name) {
             return;
         }
-        if let Ok(upvar) = env.get(*name) {
+        if let Ok(upvar) = env.get_local(*name) {
             upvars.insert(*name, Some(upvar));
         }
     }
@@ -61,7 +61,7 @@ impl<'a> Visit<'a> for CollectUpvars<'_> {
             self.visit_expr(init)
         }
         // a bound name can never be an upvar
-        self.blacklist.insert(*name);
+        self.bind_name(name);
     }
 
     fn visit_function(&mut self, f: &'a cl_ast::Function) {