diff --git a/homeassistant/components/sensor/whois.py b/homeassistant/components/sensor/whois.py
index 9f50a4c13db..771c4bc9d73 100644
--- a/homeassistant/components/sensor/whois.py
+++ b/homeassistant/components/sensor/whois.py
@@ -47,14 +47,13 @@ def setup_platform(hass, config, add_devices, discovery_info=None):
         if 'expiration_date' in get_whois(domain, normalized=True):
             add_devices([WhoisSensor(name, domain)], True)
         else:
-            _LOGGER.warning(
+            _LOGGER.error(
                 "WHOIS lookup for %s didn't contain expiration_date",
                 domain)
             return
     except WhoisException as ex:
-        _LOGGER.error("Exception %s occurred during WHOIS lookup for %s",
-                      ex,
-                      domain)
+        _LOGGER.error(
+            "Exception %s occurred during WHOIS lookup for %s", ex, domain)
         return
 
 
@@ -71,10 +70,7 @@ class WhoisSensor(Entity):
         self._domain = domain
 
         self._state = None
-        self._data = None
-        self._updated_date = None
-        self._expiration_date = None
-        self._name_servers = []
+        self._attributes = None
 
     @property
     def name(self):
@@ -99,38 +95,52 @@ class WhoisSensor(Entity):
     @property
     def device_state_attributes(self):
         """Get the more info attributes."""
-        if self._data:
-            updated_formatted = self._updated_date.isoformat()
-            expires_formatted = self._expiration_date.isoformat()
+        return self._attributes
 
-            return {
-                ATTR_NAME_SERVERS: ' '.join(self._name_servers),
-                ATTR_REGISTRAR: self._data['registrar'][0],
-                ATTR_UPDATED: updated_formatted,
-                ATTR_EXPIRES: expires_formatted,
-            }
+    def _empty_state_and_attributes(self):
+        """Empty the state and attributes on an error."""
+        self._state = None
+        self._attributes = None
 
     def update(self):
-        """Get the current WHOIS data for hostname."""
+        """Get the current WHOIS data for the domain."""
         from pythonwhois.shared import WhoisException
 
         try:
             response = self.whois(self._domain, normalized=True)
         except WhoisException as ex:
             _LOGGER.error("Exception %s occurred during WHOIS lookup", ex)
+            self._empty_state_and_attributes()
             return
 
         if response:
-            self._data = response
+            if 'expiration_date' not in response:
+                _LOGGER.error(
+                    "Failed to find expiration_date in whois lookup response. "
+                    "Did find: %s", ', '.join(response.keys()))
+                self._empty_state_and_attributes()
+                return
 
-            if self._data['nameservers']:
-                self._name_servers = self._data['nameservers']
+            if not response['expiration_date']:
+                _LOGGER.error("Whois response contains empty expiration_date")
+                self._empty_state_and_attributes()
+                return
 
-            if 'expiration_date' in self._data:
-                self._expiration_date = self._data['expiration_date'][0]
-            if 'updated_date' in self._data:
-                self._updated_date = self._data['updated_date'][0]
+            attrs = {}
 
-            time_delta = (self._expiration_date - self._expiration_date.now())
+            expiration_date = response['expiration_date'][0]
+            attrs[ATTR_EXPIRES] = expiration_date.isoformat()
 
+            if 'nameservers' in response:
+                attrs[ATTR_NAME_SERVERS] = ' '.join(response['nameservers'])
+
+            if 'updated_date' in response:
+                attrs[ATTR_UPDATED] = response['updated_date'][0].isoformat()
+
+            if 'registrar' in response:
+                attrs[ATTR_REGISTRAR] = response['registrar'][0]
+
+            time_delta = (expiration_date - expiration_date.now())
+
+            self._attributes = attrs
             self._state = time_delta.days