diff --git a/src/arobject.h b/src/arobject.h
index 6b7d89a..497bc3e 100644
--- a/src/arobject.h
+++ b/src/arobject.h
@@ -98,12 +98,19 @@ struct argon_function_struct {
   uint64_t column;
 };
 
+struct built_in_slot {
+  built_in_fields field;
+  ArgonObject*value;
+};
+
 // full definition of ArgonObject (no typedef again!)
 struct ArgonObject {
   ArgonType type;
   ArgonType child_type;
   struct hashmap_GC *dict;
-  ArgonObject* Builtin_slots[BUILT_IN_FIELDS_COUNT];
+  struct built_in_slot* built_in_slot;
+  size_t built_in_slot_size;
+  size_t built_in_slot_length;
   bool as_bool;
   union {
     struct as_number {
diff --git a/src/runtime/objects/number/number.c b/src/runtime/objects/number/number.c
index 2d6c687..d773bd4 100644
--- a/src/runtime/objects/number/number.c
+++ b/src/runtime/objects/number/number.c
@@ -498,7 +498,6 @@ void init_small_ints() {
     small_ints[i].type = TYPE_NUMBER;
     small_ints[i].dict = createHashmap_GC();
     add_builtin_field(&small_ints[i], __class__, ARGON_NUMBER_TYPE);
-    add_builtin_field(&small_ints[i], __base__, BASE_CLASS);
     small_ints[i].value.as_number.is_int64 = true;
     small_ints[i].value.as_number.n.i64 = n;
     small_ints[i].as_bool = n;
diff --git a/src/runtime/objects/object.c b/src/runtime/objects/object.c
index 0e2df97..e1e9410 100644
--- a/src/runtime/objects/object.c
+++ b/src/runtime/objects/object.c
@@ -12,6 +12,20 @@
 #include <stdio.h>
 #include <string.h>
 
+int strcmp_len(const char *s1, size_t len, const char *s2) {
+  size_t s2len = strlen(s2); // length of null-terminated string
+  size_t n = (len < s2len) ? len : s2len;
+
+  int cmp = memcmp(s1, s2, n);
+  if (cmp != 0)
+    return cmp;
+
+  // If prefixes match, decide based on length
+  if (len == s2len)
+    return 0;
+  return (len < s2len) ? -1 : 1;
+}
+
 ArgonObject *BASE_CLASS = NULL;
 
 const char *built_in_field_names[BUILT_IN_FIELDS_COUNT] = {
@@ -21,10 +35,11 @@ const char *built_in_field_names[BUILT_IN_FIELDS_COUNT] = {
     "__binding__", "__function__", "address",      "__call__",
     "__number__",  "log",          "length",       "__getattribute__"};
 
-
 ArgonObject *new_object() {
   ArgonObject *object = ar_alloc(sizeof(ArgonObject));
-  memset(object->Builtin_slots, 0, sizeof(object->Builtin_slots));
+  object->built_in_slot = NULL;
+  object->built_in_slot_size = 0;
+  object->built_in_slot_length = 0;
   object->type = TYPE_OBJECT;
   object->dict = NULL;
   object->as_bool = true;
@@ -46,16 +61,31 @@ ArgonObject *new_instance(ArgonObject *of) {
 
 inline void add_builtin_field(ArgonObject *target, built_in_fields field,
                               ArgonObject *object) {
-  target->Builtin_slots[field] = object;
+  for (size_t i = 0; i < target->built_in_slot_length; i++) {
+    if (target->built_in_slot[i].field == field) {
+      target->built_in_slot[i].value = object;
+      return;
+    }
+  }
+  size_t position = target->built_in_slot_length++;
+  if (target->built_in_slot_length > target->built_in_slot_size) {
+    target->built_in_slot_size *= 2;
+    if (target->built_in_slot_size == 0) target->built_in_slot_size = 2;
+    else if (target->built_in_slot_size>BUILT_IN_FIELDS_COUNT) target->built_in_slot_size = BUILT_IN_FIELDS_COUNT;
+    target->built_in_slot =
+        ar_realloc(target->built_in_slot, target->built_in_slot_size *
+                                              sizeof(struct built_in_slot));
+  }
+  target->built_in_slot[position] = (struct built_in_slot){field, object};
   // hashmap_insert_GC(target->dict, built_in_field_hashes[field],
   //                   (char *)built_in_field_names[field], object, 0);
 }
 
-void add_field(ArgonObject *target, char *name, uint64_t hash,
-               ArgonObject *object) {
+void add_field_l(ArgonObject *target, char *name, uint64_t hash, size_t length,
+                 ArgonObject *object) {
   for (size_t i = 0; i < BUILT_IN_FIELDS_COUNT; i++) {
-    if (strcmp(name, built_in_field_names[i])) {
-      target->Builtin_slots[i] = object;
+    if (strcmp_len(name, length, built_in_field_names[i]) == 0) {
+      add_builtin_field(target, i, object);
       return;
     }
   }
@@ -71,8 +101,7 @@ ArgonObject *bind_object_to_function(ArgonObject *object,
   add_builtin_field(bound_method_wrapper, __class__, ARGON_METHOD_TYPE);
   add_builtin_field(bound_method_wrapper, __binding__, object);
   add_builtin_field(bound_method_wrapper, __function__, function);
-  ArgonObject *function_name =
-      get_builtin_field(function, __name__);
+  ArgonObject *function_name = get_builtin_field(function, __name__);
   if (function_name)
     add_builtin_field(bound_method_wrapper, __name__, function_name);
   return bound_method_wrapper;
@@ -100,8 +129,8 @@ ArgonObject *get_field_l(ArgonObject *target, char *name, uint64_t hash,
                          size_t length, bool recursive,
                          bool disable_method_wrapper) {
   for (size_t i = 0; i < BUILT_IN_FIELDS_COUNT; i++) {
-    if (strcmp(name, built_in_field_names[i])) {
-      return target->Builtin_slots[i];
+    if (strcmp_len(name, length, built_in_field_names[i]) == 0) {
+      return get_builtin_field(target, i);
     }
   }
   if (!target->dict)
@@ -112,28 +141,35 @@ ArgonObject *get_field_l(ArgonObject *target, char *name, uint64_t hash,
   ArgonObject *binding = target;
   if (disable_method_wrapper)
     binding = NULL;
-  return get_field_for_class_l(
-      get_builtin_field(target, __class__), name,
-      hash, length, binding);
+  return get_field_for_class_l(get_builtin_field(target, __class__), name, hash,
+                               length, binding);
 }
 
 ArgonObject *get_builtin_field_for_class(ArgonObject *target,
                                          built_in_fields field,
                                          ArgonObject *binding_object) {
-  ArgonObject *object = get_builtin_field(target, field);
-  if (object) {
-    if ((object->type == TYPE_FUNCTION ||
-         object->type == TYPE_NATIVE_FUNCTION) &&
-        binding_object) {
-      object = bind_object_to_function(binding_object, object);
+  while (target) {
+    ArgonObject *object = get_builtin_field(target, field);
+    if (object) {
+      if ((object->type == TYPE_FUNCTION ||
+           object->type == TYPE_NATIVE_FUNCTION) &&
+          binding_object) {
+        object = bind_object_to_function(binding_object, object);
+      }
+      return object;
     }
-    return object;
+    target = get_builtin_field(target, __base__);
   }
   return NULL;
 }
 
 ArgonObject *get_builtin_field(ArgonObject *target, built_in_fields field) {
-  return target->Builtin_slots[field];
+  for (size_t i = 0; i < target->built_in_slot_length; i++) {
+    if (target->built_in_slot[i].field == field) {
+      return target->built_in_slot[i].value;
+    }
+  }
+  return NULL;
   // ArgonObject *object =
   //     hashmap_lookup_GC(target->dict, built_in_field_hashes[field]);
   // if (!recursive || object)
diff --git a/src/runtime/objects/object.h b/src/runtime/objects/object.h
index 2dfe02b..ffd13c9 100644
--- a/src/runtime/objects/object.h
+++ b/src/runtime/objects/object.h
@@ -21,8 +21,8 @@ ArgonObject *new_instance(ArgonObject * of);
 void add_builtin_field(ArgonObject *target, built_in_fields field,
                        ArgonObject *object);
 
-void add_field(ArgonObject *target, char *name, uint64_t hash,
-               ArgonObject *object);
+void add_field_l(ArgonObject *target, char *name, uint64_t hash, size_t length,
+                 ArgonObject *object);
 
 ArgonObject *bind_object_to_function(ArgonObject *object,
                                      ArgonObject *function);
diff --git a/tests/iteration-test.ar b/tests/iteration-test.ar
index 0f7853b..2c929db 100644
--- a/tests/iteration-test.ar
+++ b/tests/iteration-test.ar
@@ -1,3 +1,3 @@
-let i = 1e6
+let i = 1e7
 while (i) do
   i=i-1
\ No newline at end of file