diff --git a/lexical-env.rkt b/lexical-env.rkt
index ffc6345..a54516c 100644
--- a/lexical-env.rkt
+++ b/lexical-env.rkt
@@ -40,16 +40,16 @@
                           [else
                            (loop (rest cenv) (add1 depth))])]
                    
-                   [(symbol? elt)
+                   [(NamedBinding? elt)
                     (cond
-                      [(eq? elt name)
+                      [(eq? (NamedBinding-name elt) name)
                        (make-EnvLexicalReference depth #f)]
                       [else
                        (loop (rest cenv) (add1 depth))])]
 
                    [(box? elt)
                     (cond
-                      [(eq? (unbox elt) name)
+                      [(eq? (NamedBinding-name (unbox elt)) name)
                        (make-EnvLexicalReference depth #t)]
                       [else
                        (loop (rest cenv) (add1 depth))])]
@@ -81,12 +81,14 @@
 
 (: extend-lexical-environment/names (CompileTimeEnvironment (Listof Symbol) -> CompileTimeEnvironment))
 (define (extend-lexical-environment/names cenv names)
-  (append names cenv))
+  (append (map make-NamedBinding names) cenv))
 
 
 (: extend-lexical-environment/boxed-names (CompileTimeEnvironment (Listof Symbol) -> CompileTimeEnvironment))
 (define (extend-lexical-environment/boxed-names cenv names)
-  (append (map (inst box Symbol) names) cenv))
+  (append (map (inst box NamedBinding) 
+               (map make-NamedBinding names))
+          cenv))
 
 
 (: extend-lexical-environment/placeholders
diff --git a/lexical-structs.rkt b/lexical-structs.rkt
index cfca301..e3fde45 100644
--- a/lexical-structs.rkt
+++ b/lexical-structs.rkt
@@ -13,14 +13,17 @@
   #:transparent)
 
 
+(define-struct: NamedBinding ([name : Symbol]))
 
 
 (define-type CompileTimeEnvironmentEntry (U Prefix ;; a prefix
-                                            Symbol
-                                            (Boxof Symbol) ;; A boxed local
+                                            NamedBinding
+                                            (Boxof NamedBinding) ;; A boxed local
                                             False))
 
 
+
+
 ;; A compile-time environment is a (listof (listof symbol)).
 ;; A lexical address is either a 2-tuple (depth pos), or 'not-found.
 (define-type CompileTimeEnvironment (Listof CompileTimeEnvironmentEntry))