diff --git a/homeassistant/components/device_sun_light_trigger.py b/homeassistant/components/device_sun_light_trigger.py
index 4740336767f..c53fff0e4f3 100644
--- a/homeassistant/components/device_sun_light_trigger.py
+++ b/homeassistant/components/device_sun_light_trigger.py
@@ -6,8 +6,9 @@ Provides functionality to turn on lights based on
 the state of the sun and devices.
 """
 import logging
-from datetime import datetime, timedelta
+from datetime import timedelta
 
+import homeassistant.util.dt as dt_util
 from homeassistant.const import STATE_HOME, STATE_NOT_HOME
 from . import light, sun, device_tracker, group
 
@@ -115,7 +116,7 @@ def setup(hass, config):
            new_state.state == STATE_HOME:
 
             # These variables are needed for the elif check
-            now = datetime.now()
+            now = dt_util.now()
             start_point = calc_time_for_light_when_sunset()
 
             # Do we need lights?
diff --git a/homeassistant/components/device_tracker/nmap_tracker.py b/homeassistant/components/device_tracker/nmap_tracker.py
index b2d009ab199..ccd04f6cda1 100644
--- a/homeassistant/components/device_tracker/nmap_tracker.py
+++ b/homeassistant/components/device_tracker/nmap_tracker.py
@@ -21,7 +21,7 @@ The IP addresses to scan in the network-prefix notation (192.168.1.1/24) or
 the range notation (192.168.1.1-255).
 """
 import logging
-from datetime import timedelta, datetime
+from datetime import timedelta
 from collections import namedtuple
 import subprocess
 import re
@@ -29,6 +29,7 @@ import re
 from libnmap.process import NmapProcess
 from libnmap.parser import NmapParser, NmapParserException
 
+import homeassistant.util.dt as dt_util
 from homeassistant.const import CONF_HOSTS
 from homeassistant.helpers import validate_config
 from homeassistant.util import Throttle, convert
@@ -106,7 +107,7 @@ class NmapDeviceScanner(object):
             Returns True if successful, False otherwise. """
         try:
             results = NmapParser.parse(stdout)
-            now = datetime.now()
+            now = dt_util.now()
             self.last_results = []
             for host in results.hosts:
                 if host.is_up():
@@ -140,7 +141,7 @@ class NmapDeviceScanner(object):
         options = "-F --host-timeout 5"
         exclude_targets = set()
         if self.home_interval:
-            now = datetime.now()
+            now = dt_util.now()
             for host in self.last_results:
                 if host.last_update + self.home_interval > now:
                     exclude_targets.add(host)
diff --git a/homeassistant/components/scheduler/time.py b/homeassistant/components/scheduler/time.py
index 94eabe7dd2b..793f33d0502 100644
--- a/homeassistant/components/scheduler/time.py
+++ b/homeassistant/components/scheduler/time.py
@@ -13,9 +13,10 @@ which time.
 }
 
 """
-from datetime import datetime, timedelta
+from datetime import timedelta
 import logging
 
+import homeassistant.util.dt as dt_util
 from homeassistant.components.scheduler import ServiceEventListener
 
 _LOGGER = logging.getLogger(__name__)
@@ -46,14 +47,12 @@ class TimeEventListener(ServiceEventListener):
     def schedule(self, hass):
         """ Schedule this event so that it will be called. """
 
-        next_time = datetime.now().replace(hour=self.hour,
-                                           minute=self.minute,
-                                           second=self.second,
-                                           microsecond=0)
+        next_time = dt_util.now().replace(
+            hour=self.hour, minute=self.minute, second=self.second)
 
         # Calculate the next time the event should be executed.
         # That is the next day that the schedule is configured to run
-        while next_time < datetime.now() or \
+        while next_time < dt_util.now() or \
                 next_time.weekday() not in self.my_schedule.days:
 
             next_time = next_time + timedelta(days=1)
diff --git a/homeassistant/components/sun.py b/homeassistant/components/sun.py
index 208d17167c6..ae33f86f01e 100644
--- a/homeassistant/components/sun.py
+++ b/homeassistant/components/sun.py
@@ -22,7 +22,7 @@ which event (sunset or sunrise) and the offset.
 
 """
 import logging
-from datetime import datetime, timedelta
+from datetime import timedelta
 
 try:
     import ephem
@@ -233,7 +233,7 @@ class SunEventListener(ServiceEventListener):
         else:
             next_time = next_event + self.offset
 
-        while next_time < datetime.now() or \
+        while next_time < dt_util.now() or \
                 next_time.weekday() not in self.my_schedule.days:
             next_time = next_time + timedelta(days=1)