diff --git a/src/Defun.ml b/src/Defun.ml
index 13484fb..1441922 100644
--- a/src/Defun.ml
+++ b/src/Defun.ml
@@ -65,7 +65,7 @@ let rec walk_term fs t =
     | S.LetVal (var, value, next) ->
             let fs, nNext = walk_term fs next in
             fs, T.LetVal(var, value, nNext)
-    | S.LetBlo (var, S.Lam(_, vars, body), next) ->
+    | S.LetBlo (var, S.Lam(self, vars, body), next) ->
             (* FIXME is handling of recursive functions correct? *)
             let fs, nNext = walk_term fs next in
             let fs, nBody = walk_term fs body in
@@ -77,10 +77,13 @@ let rec walk_term fs t =
                 vars
                 (S.vvars (List.tl args)) in
             let thisTag = freshTag () in
+            let selfVars = (match self with
+                | S.Self self -> Atom.Set.singleton self
+                | S.NoSelf -> Atom.Set.empty) in
             let freeVars = Atom.Set.elements @@
                 Atom.Set.diff
                     (S.fv_term body)
-                    (Atom.Set.of_list vars)
+                    (Atom.Set.union (Atom.Set.of_list vars) selfVars)
                 in
             let thisFunc =
                 T.Branch(thisTag, freeVars, nBody) in