diff --git a/lang/lifting/src/fv.rs b/lang/lifting/src/fv.rs
index 3622067bd..9566857fc 100644
--- a/lang/lifting/src/fv.rs
+++ b/lang/lifting/src/fv.rs
@@ -22,7 +22,7 @@ pub fn free_vars<T: FV>(arg: &T, ctx: &TypeCtx) -> FreeVars {
     FreeVars { fvs: v.fvs, cutoff: ctx.len() }
 }
 
-trait FV {
+pub trait FV {
     fn visit_fv(&self, v: &mut USTVisitor);
 }
 
@@ -268,7 +268,7 @@ impl Ord for FreeVar {
 }
 
 /// Visitor that collects free variables in an untyped syntax tree
-struct USTVisitor<'a> {
+pub struct USTVisitor<'a> {
     /// Set of collected free variables
     fvs: HashSet<FreeVar>,
     /// The De-Bruijn level (fst index) up to which a variable counts as free
diff --git a/lang/syntax/src/common/de_bruijn.rs b/lang/syntax/src/common/de_bruijn.rs
index ce244fdd9..537812cde 100644
--- a/lang/syntax/src/common/de_bruijn.rs
+++ b/lang/syntax/src/common/de_bruijn.rs
@@ -95,7 +95,7 @@ pub trait Leveled {
 /// Note: We use two-level de Bruijn indices. The cutoff-range only applies to
 /// the first element of a two-level de Bruijn index.
 ///
-/// Ref: https://www.cs.cornell.edu/courses/cs4110/2018fa/lectures/lecture15.pdf
+/// Ref: <https://www.cs.cornell.edu/courses/cs4110/2018fa/lectures/lecture15.pdf>
 pub trait Shift: Sized {
     /// Shift all open variables in `self` by the the value indicated with the
     /// `by` argument.