diff --git a/code/compiler/13/compiler.cpp b/code/compiler/13/compiler.cpp
index 71db20e..3d4b5ff 100644
--- a/code/compiler/13/compiler.cpp
+++ b/code/compiler/13/compiler.cpp
@@ -69,7 +69,7 @@ void compiler::translate() {
     }
     for(auto& defn : global_defs.defs_defn) {
         auto& function = defn.second->into_global(global_scp);
-        function.body->env->parent->set_mangled_name(defn.first, function.name);
+        function.body->env->get_parent()->set_mangled_name(defn.first, function.name);
     }
 }
 
diff --git a/code/compiler/13/type_env.cpp b/code/compiler/13/type_env.cpp
index 6f4fe6a..a00058d 100644
--- a/code/compiler/13/type_env.cpp
+++ b/code/compiler/13/type_env.cpp
@@ -2,6 +2,10 @@
 #include "type.hpp"
 #include "error.hpp"
 
+type_env_ptr type_env::get_parent() {
+    return parent;
+}
+
 void type_env::find_free(const type_mgr& mgr, std::set<std::string>& into) const {
     if(parent != nullptr) parent->find_free(mgr, into);
     for(auto& binding : names) {
diff --git a/code/compiler/13/type_env.hpp b/code/compiler/13/type_env.hpp
index 5292904..334ef73 100644
--- a/code/compiler/13/type_env.hpp
+++ b/code/compiler/13/type_env.hpp
@@ -10,39 +10,42 @@ using type_env_ptr = std::shared_ptr<type_env>;
 
 enum class visibility { global,local };
 
-struct type_env {
-    struct variable_data {
-        type_scheme_ptr type;
-        visibility vis;
-        std::string mangled_name;
+class type_env {
+    private:
+        struct variable_data {
+            type_scheme_ptr type;
+            visibility vis;
+            std::string mangled_name;
 
-        variable_data()
-            : variable_data(nullptr, visibility::local, "") {}
-        variable_data(type_scheme_ptr t, visibility v, std::string n)
-            : type(std::move(t)), vis(v), mangled_name(std::move(n)) {}
-    };
+            variable_data()
+                : variable_data(nullptr, visibility::local, "") {}
+            variable_data(type_scheme_ptr t, visibility v, std::string n)
+                : type(std::move(t)), vis(v), mangled_name(std::move(n)) {}
+        };
 
-    type_env_ptr parent;
-    std::map<std::string, variable_data> names;
-    std::map<std::string, type_ptr> type_names;
+        type_env_ptr parent;
+        std::map<std::string, variable_data> names;
+        std::map<std::string, type_ptr> type_names;
 
-    type_env(type_env_ptr p) : parent(std::move(p)) {}
-    type_env() : type_env(nullptr) {}
+    public:
+        type_env(type_env_ptr p) : parent(std::move(p)) {}
+        type_env() : type_env(nullptr) {}
 
-    void find_free(const type_mgr& mgr, std::set<std::string>& into) const;
-    void find_free_except(const type_mgr& mgr, const group& avoid,
-            std::set<std::string>& into) const;
-    type_scheme_ptr lookup(const std::string& name) const;
-    bool is_global(const std::string& name) const;
-    void set_mangled_name(const std::string& name, const std::string& mangled);
-    const std::string& get_mangled_name(const std::string& name) const;
-    type_ptr lookup_type(const std::string& name) const;
-    void bind(const std::string& name, type_ptr t,
-            visibility v = visibility::local);
-    void bind(const std::string& name, type_scheme_ptr t,
-            visibility v = visibility::local);
-    void bind_type(const std::string& type_name, type_ptr t);
-    void generalize(const std::string& name, const group& grp, type_mgr& mgr);
+        type_env_ptr get_parent();
+        void find_free(const type_mgr& mgr, std::set<std::string>& into) const;
+        void find_free_except(const type_mgr& mgr, const group& avoid,
+                std::set<std::string>& into) const;
+        type_scheme_ptr lookup(const std::string& name) const;
+        bool is_global(const std::string& name) const;
+        void set_mangled_name(const std::string& name, const std::string& mangled);
+        const std::string& get_mangled_name(const std::string& name) const;
+        type_ptr lookup_type(const std::string& name) const;
+        void bind(const std::string& name, type_ptr t,
+                visibility v = visibility::local);
+        void bind(const std::string& name, type_scheme_ptr t,
+                visibility v = visibility::local);
+        void bind_type(const std::string& type_name, type_ptr t);
+        void generalize(const std::string& name, const group& grp, type_mgr& mgr);
 };