diff --git a/include/pocketpy/interpreter/typeinfo.h b/include/pocketpy/interpreter/typeinfo.h
index ffd0b060..c3c500bd 100644
--- a/include/pocketpy/interpreter/typeinfo.h
+++ b/include/pocketpy/interpreter/typeinfo.h
@@ -6,6 +6,7 @@
 typedef struct py_TypeInfo {
     py_Name name;
     py_Type base;
+    struct py_TypeInfo* base_ti;
 
     py_TValue self;
     py_TValue module;  // the module where the type is defined
diff --git a/src/interpreter/ceval.c b/src/interpreter/ceval.c
index 98aac846..cf8591b6 100644
--- a/src/interpreter/ceval.c
+++ b/src/interpreter/ceval.c
@@ -894,7 +894,7 @@ FrameResult VM__run_top_frame(VM* self) {
                     // call on_end_subclass
                     py_TypeInfo* ti = TypeList__get(&self->types, py_totype(TOP()));
                     if(ti->base != tp_object) {
-                        py_TypeInfo* base_ti = TypeList__get(&self->types, ti->base);
+                        py_TypeInfo* base_ti = ti->base_ti;
                         if(base_ti->on_end_subclass) base_ti->on_end_subclass(ti);
                     }
                 }
diff --git a/src/interpreter/vm.c b/src/interpreter/vm.c
index 22838690..7ae275cb 100644
--- a/src/interpreter/vm.c
+++ b/src/interpreter/vm.c
@@ -33,11 +33,13 @@ static void py_TypeInfo__ctor(py_TypeInfo* self,
                               py_Name name,
                               py_Type index,
                               py_Type base,
+                              py_TypeInfo* base_ti,
                               py_TValue module) {
     memset(self, 0, sizeof(py_TypeInfo));
 
     self->name = name;
     self->base = base;
+    self->base_ti = base_ti;
 
     // create type object with __dict__
     ManagedHeap* heap = &pk_current_vm->heap;
@@ -323,7 +325,7 @@ py_Type pk_newtype(const char* name,
     if(base_ti && base_ti->is_sealed) {
         c11__abort("type '%s' is not an acceptable base type", py_name2str(base_ti->name));
     }
-    py_TypeInfo__ctor(ti, py_name(name), index, base, module ? *module : *py_NIL);
+    py_TypeInfo__ctor(ti, py_name(name), index, base, base_ti, module ? *module : *py_NIL);
     if(!dtor && base) dtor = base_ti->dtor;
     ti->dtor = dtor;
     ti->is_python = is_python;
@@ -697,6 +699,4 @@ bool pk_wrapper__NotImplementedError(int argc, py_Ref argv) {
     return py_exception(tp_NotImplementedError, "");
 }
 
-py_TypeInfo* pk__type_info(py_Type type) {
-    return TypeList__get(&pk_current_vm->types, type);
-}
+py_TypeInfo* pk__type_info(py_Type type) { return TypeList__get(&pk_current_vm->types, type); }
diff --git a/src/modules/enum.c b/src/modules/enum.c
index c2f170a4..11bb57f9 100644
--- a/src/modules/enum.c
+++ b/src/modules/enum.c
@@ -86,6 +86,5 @@ void pk__add_module_enum() {
     py_bindproperty(type, "name", Enum__name, NULL);
     py_bindproperty(type, "value", Enum__value, NULL);
 
-    py_TypeInfo* ti = pk__type_info(type);
-    ti->on_end_subclass = Enum__on_end_subclass;
+    pk__type_info(type)->on_end_subclass = Enum__on_end_subclass;
 }
\ No newline at end of file
diff --git a/src/public/internal.c b/src/public/internal.c
index 495b50f2..6b086d99 100644
--- a/src/public/internal.c
+++ b/src/public/internal.c
@@ -190,24 +190,22 @@ bool pk_loadmethod(py_StackRef self, py_Name name) {
 
 py_Ref py_tpfindmagic(py_Type t, py_Name name) {
     assert(py_ismagicname(name));
-    TypeList* types = &pk_current_vm->types;
+    py_TypeInfo* ti = pk__type_info(t);
     do {
-        py_TypeInfo* ti = TypeList__get(types, t);
         py_Ref f = &ti->magic[name];
         if(!py_isnil(f)) return f;
-        t = ti->base;
-    } while(t);
+        ti = ti->base_ti;
+    } while(ti);
     return NULL;
 }
 
 py_Ref py_tpfindname(py_Type t, py_Name name) {
-    TypeList* types = &pk_current_vm->types;
+    py_TypeInfo* ti = pk__type_info(t);
     do {
-        py_TypeInfo* ti = TypeList__get(types, t);
         py_Ref res = py_getdict(&ti->self, name);
         if(res) return res;
-        t = ti->base;
-    } while(t);
+        ti = ti->base_ti;
+    } while(ti);
     return NULL;
 }
 
diff --git a/src/public/py_object.c b/src/public/py_object.c
index fd577130..3f7c2f02 100644
--- a/src/public/py_object.c
+++ b/src/public/py_object.c
@@ -74,7 +74,7 @@ static bool type__base__(int argc, py_Ref argv) {
     PY_CHECK_ARGC(1);
     py_TypeInfo* ti = pk__type_info(py_totype(argv));
     if(ti->base) {
-        py_assign(py_retval(), py_tpobject(ti->base));
+        py_assign(py_retval(), &ti->base_ti->self);
     } else {
         py_newnone(py_retval());
     }
diff --git a/src/public/py_ops.c b/src/public/py_ops.c
index da2a1aab..30b2bfa0 100644
--- a/src/public/py_ops.c
+++ b/src/public/py_ops.c
@@ -45,10 +45,8 @@ int py_bool(py_Ref val) {
 }
 
 bool py_hash(py_Ref val, int64_t* out) {
-    py_Type t = val->type;
-    TypeList* types = &pk_current_vm->types;
+    py_TypeInfo* ti = pk__type_info(val->type);
     do {
-        py_TypeInfo* ti = TypeList__get(types, t);
         py_Ref _hash = &ti->magic[__hash__];
         if(py_isnone(_hash)) break;
         py_Ref _eq = &ti->magic[__eq__];
@@ -59,8 +57,8 @@ bool py_hash(py_Ref val, int64_t* out) {
             *out = py_toint(py_retval());
             return true;
         }
-        t = ti->base;
-    } while(t);
+        ti = ti->base_ti;
+    } while(ti);
     return TypeError("unhashable type: '%t'", val->type);
 }