diff --git a/homeassistant/config.py b/homeassistant/config.py
index a2862c95216..2714f066035 100644
--- a/homeassistant/config.py
+++ b/homeassistant/config.py
@@ -4,7 +4,6 @@ from collections import OrderedDict
 import logging
 import os
 import shutil
-from types import MappingProxyType
 # pylint: disable=unused-import
 from typing import Any, List, Tuple  # NOQA
 
@@ -121,9 +120,8 @@ CORE_CONFIG_SCHEMA = vol.Schema({
     vol.Optional(CONF_TEMPERATURE_UNIT): cv.temperature_unit,
     CONF_UNIT_SYSTEM: cv.unit_system,
     CONF_TIME_ZONE: cv.time_zone,
-    vol.Required(CONF_CUSTOMIZE,
-                 default=MappingProxyType({})): vol.All(
-                     _convert_old_config, [CUSTOMIZE_SCHEMA_ENTRY]),
+    vol.Optional(CONF_CUSTOMIZE, default=[]): vol.All(
+        _convert_old_config, [CUSTOMIZE_SCHEMA_ENTRY]),
     vol.Optional(CONF_PACKAGES, default={}): PACKAGES_CONFIG_SCHEMA,
 })
 
@@ -308,7 +306,9 @@ def async_process_ha_core_config(hass, config):
     if CONF_TIME_ZONE in config:
         set_time_zone(config.get(CONF_TIME_ZONE))
 
-    set_customize(hass, config.get(CONF_CUSTOMIZE) or {})
+    customize = merge_packages_customize(
+        config[CONF_CUSTOMIZE], config[CONF_PACKAGES])
+    set_customize(hass, customize)
 
     if CONF_UNIT_SYSTEM in config:
         if config[CONF_UNIT_SYSTEM] == CONF_UNIT_SYSTEM_IMPERIAL:
@@ -407,6 +407,8 @@ def merge_packages_config(config, packages):
     PACKAGES_CONFIG_SCHEMA(packages)
     for pack_name, pack_conf in packages.items():
         for comp_name, comp_conf in pack_conf.items():
+            if comp_name == CONF_CORE:
+                continue
             component = get_component(comp_name)
 
             if component is None:
@@ -459,3 +461,18 @@ def merge_packages_config(config, packages):
             config[comp_name] = comp_conf
 
     return config
+
+
+def merge_packages_customize(customize, packages):
+    """Merge customize from packages."""
+    schema = vol.Schema({
+        vol.Optional(CONF_CORE): vol.Schema({
+            CONF_CUSTOMIZE: vol.All(
+                _convert_old_config, [CUSTOMIZE_SCHEMA_ENTRY])})
+    }, extra=vol.ALLOW_EXTRA)
+
+    cust = list(customize)
+    for pkg in packages.values():
+        conf = schema(pkg)
+        cust.extend(conf.get(CONF_CORE, {}).get(CONF_CUSTOMIZE, []))
+    return cust
diff --git a/tests/test_config.py b/tests/test_config.py
index 39769486056..1d647cb2c92 100644
--- a/tests/test_config.py
+++ b/tests/test_config.py
@@ -473,7 +473,6 @@ def test_merge_type_mismatch(merge_log_err):
 def test_merge_once_only(merge_log_err):
     """Test if we have a merge for a comp that may occur only once."""
     packages = {
-        'pack_1': {'homeassistant': {}},
         'pack_2': {
             'mqtt': {},
             'api': {},  # No config schema
@@ -484,7 +483,7 @@ def test_merge_once_only(merge_log_err):
         'mqtt': {}, 'api': {}
     }
     config_util.merge_packages_config(config, packages)
-    assert merge_log_err.call_count == 3
+    assert merge_log_err.call_count == 2
     assert len(config) == 3
 
 
@@ -519,3 +518,29 @@ def test_merge_duplicate_keys(merge_log_err):
     assert merge_log_err.call_count == 1
     assert len(config) == 2
     assert len(config['input_select']) == 1
+
+
+@pytest.mark.asyncio
+def test_merge_customize(hass):
+    """Test loading core config onto hass object."""
+    core_config = {
+        'latitude': 60,
+        'longitude': 50,
+        'elevation': 25,
+        'name': 'Huis',
+        CONF_UNIT_SYSTEM: CONF_UNIT_SYSTEM_IMPERIAL,
+        'time_zone': 'GMT',
+        'customize': {'a.a': {'friendly_name': 'A'}},
+        'packages': {'pkg1': {'homeassistant': {'customize': {
+            'b.b': {'friendly_name': 'BB'}}}}},
+    }
+    yield from config_util.async_process_ha_core_config(hass, core_config)
+
+    entity = Entity()
+    entity.entity_id = 'b.b'
+    entity.hass = hass
+    yield from entity.async_update_ha_state()
+
+    state = hass.states.get('b.b')
+    assert state is not None
+    assert state.attributes['friendly_name'] == 'BB'