diff --git a/cosmoz-omnitable-column-date-mixin.html b/cosmoz-omnitable-column-date-mixin.html
index 523f2253..b789c83e 100644
--- a/cosmoz-omnitable-column-date-mixin.html
+++ b/cosmoz-omnitable-column-date-mixin.html
@@ -3,219 +3,227 @@
 
 <link rel="import" href="cosmoz-omnitable-column-range-mixin.html" />
 <script>
-window.Cosmoz = window.Cosmoz || {};
+(() => {
+	window.Cosmoz = window.Cosmoz || {};
 
-/**
- * @polymer
- * @mixinFunction
- * @appliesMixin Cosmoz.RangeColumnMixin
-
- * @param {class} base The base class
- * @returns {class} The base class with the mixin applied
- */
-Cosmoz.DateColumnMixin = Polymer.dedupingMixin(base =>
-	/**
-	 * @polymer
-	 * @mixinClass
-	 */
-	class extends Cosmoz.RangeColumnMixin(base) {
-		static get properties() {
-			return {
-				max: {
-					type: Date,
-					value: null
-				},
-
-				min: {
-					type: Date,
-					value: null
-				},
-
-				_filterText: {
-					type: String,
-					computed: '_computeFilterText(filter.*, formatter)'
-				},
-
-				width: {
-					type: String,
-					value: '100px'
-				},
-
-				editWidth: {
-					type: String,
-					value: '150px'
-				},
-
-				/**
-				 * No need to grow, as the values in a date column should have known fixed width
-				 * @returns {String} Default flex
-				 */
-				flex: {
-					type: String,
-					value: '0'
-				},
-				formatter: {
-					type: Object,
-					computed: '_computeFormatter(locale)'
-				}
-			};
+	const toLocalISOString = date => {
+		if (!(date instanceof Date)) {
+			return null;
 		}
+		const pad = number => number < 10 ? '0' + number : number;
+		return date.getFullYear() +
+		'-' + pad(date.getMonth() + 1) +
+		'-' + pad(date.getDate()) +
+		'T' + pad(date.getHours()) +
+		':' + pad(date.getMinutes()) +
+		':' + pad(date.getSeconds()) +
+		'.' + (date.getMilliseconds() / 1000).toFixed(3).slice(2, 5);
+	};
 
+	/**
+	* @polymer
+	* @mixinFunction
+	* @appliesMixin Cosmoz.RangeColumnMixin
+
+	* @param {class} base The base class
+	* @returns {class} The base class with the mixin applied
+	*/
+	Cosmoz.DateColumnMixin = Polymer.dedupingMixin(base =>
 		/**
-		 * Converts an value to date optionaly limiting it.
-		 *
-		 * @param  {Date|String} value   Value to convert to date
-		 * @param  {Date|String} limit   Value used to limit the date
-		 * @param  {Function} limitFunc  Function used to limit the date (Math.min|Math.max)
-		 * @returns {Date|void} Value converted to date optionaly limitated
+		 * @polymer
+		 * @mixinClass
 		 */
-		toDate(value, limit, limitFunc) {
-			if (value == null || value === '') {
-				return;
+		class extends Cosmoz.RangeColumnMixin(base) {
+			static get properties() {
+				return {
+					max: {
+						type: Date,
+						value: null
+					},
+
+					min: {
+						type: Date,
+						value: null
+					},
+
+					_filterText: {
+						type: String,
+						computed: '_computeFilterText(filter.*, formatter)'
+					},
+
+					width: {
+						type: String,
+						value: '100px'
+					},
+
+					editWidth: {
+						type: String,
+						value: '150px'
+					},
+
+					/**
+					 * No need to grow, as the values in a date column should have known fixed width
+					 * @returns {String} Default flex
+					 */
+					flex: {
+						type: String,
+						value: '0'
+					},
+					formatter: {
+						type: Object,
+						computed: '_computeFormatter(locale)'
+					}
+				};
 			}
 
-			// convert value to Date
-			let date = value;
-			if (!(date instanceof Date)) {
-				// if the value is an ISO string, make sure that it has an explicit timezone
-				if (typeof value === 'string') {
-					date = this.getAbsoluteISOString(date);
+			/**
+			 * Converts an value to date optionaly limiting it.
+			 *
+			 * @param  {Date|String} value   Value to convert to date
+			 * @param  {Date|String} limit   Value used to limit the date
+			 * @param  {Function} limitFunc  Function used to limit the date (Math.min|Math.max)
+			 * @returns {Date|void} Value converted to date optionaly limitated
+			 */
+			toDate(value, limit, limitFunc) {
+				if (value == null || value === '') {
+					return;
 				}
 
-				date = new Date(date);
-			}
+				// convert value to Date
+				let date = value;
+				if (!(date instanceof Date)) {
+					// if the value is an ISO string, make sure that it has an explicit timezone
+					if (typeof value === 'string') {
+						date = this.getAbsoluteISOString(date);
+					}
 
-			if (Number.isNaN(date.getTime())) {
-				return null;
-			}
-
-			if (limitFunc == null || limit == null) {
-				return date;
-			}
+					date = new Date(date);
+				}
 
-			const lDate = this.toDate(limit);
-			if (lDate == null) {
-				return date;
-			}
+				if (Number.isNaN(date.getTime())) {
+					return null;
+				}
 
-			const comparableDate = this.getComparableValue(date),
-				comparableLDate = this.getComparableValue(lDate),
-				limitedValue = limitFunc(comparableDate, comparableLDate);
-			return limitedValue === comparableDate ? date : lDate;
-		}
+				if (limitFunc == null || limit == null) {
+					return date;
+				}
 
-		toValue() {
-			return this.toDate.apply(this, arguments);
-		}
+				const lDate = this.toDate(limit);
+				if (lDate == null) {
+					return date;
+				}
 
-		/**
-		 * Get comparable number from date
-		 *
-		 * @param  {Object} item       Item to be processed
-		 * @param  {String} valuePath  Property path
-		 * @returns {Number|void} Valid value or void
-		 */
-		getComparableValue(item, valuePath) {
-			const value = super.getComparableValue(item, valuePath);
-			if (value == null) {
-				return;
+				const comparableDate = this.getComparableValue(date),
+					comparableLDate = this.getComparableValue(lDate),
+					limitedValue = limitFunc(comparableDate, comparableLDate);
+				return limitedValue === comparableDate ? date : lDate;
 			}
-			return this.toNumber(value.getTime());
-		}
 
-		/**
-		 * Get date of item as string
-		 *
-		 * @param  {Object} item                       Item to be processed
-		 * @param  {String} valuePath = this.valuePath Property path
-		 * @param  {Object} formatter = this.formatter Property formatter
-		 * @returns {String}                           Date rendered as string or 'Invalid Date'
-		 */
-		getString(item, valuePath = this.valuePath, formatter = this.formatter) {
-			const value = this.toValue(this.get(valuePath, item));
-			if (value === undefined) {
-				return '';
+			toValue() {
+				return this.toDate.apply(this, arguments);
 			}
-			if (value === null) {
-				return 'Invalid Date';
+
+			/**
+			 * Get comparable number from date
+			 *
+			 * @param  {Object} item       Item to be processed
+			 * @param  {String} valuePath  Property path
+			 * @returns {Number|void} Valid value or void
+			 */
+			getComparableValue(item, valuePath) {
+				const value = super.getComparableValue(item, valuePath);
+				if (value == null) {
+					return;
+				}
+				return this.toNumber(value.getTime());
 			}
-			return this.renderValue(value, formatter);
-		}
 
-		/**
-		 * Computes the local timezone and adds it to a local ISO string
-		 * @param  {String} localISOString an ISO date string, without timezone info
-		 * @return {String}                an ISO date string, with timezone info
-		 */
-		getAbsoluteISOString(localISOString) {
-			// Most browsers use local timezone when no timezone is specified
-			// but Safari uses UTC, so we set it implicitly
-			// TODO: Consider removing this when/if Safari handles local timezone correctly
-			if (localISOString.length === 19) {
-				return localISOString + this._getTimezoneString(localISOString);
+			/**
+			 * Get date of item as string
+			 *
+			 * @param  {Object} item                       Item to be processed
+			 * @param  {String} valuePath = this.valuePath Property path
+			 * @param  {Object} formatter = this.formatter Property formatter
+			 * @returns {String}                           Date rendered as string or 'Invalid Date'
+			 */
+			getString(item, valuePath = this.valuePath, formatter = this.formatter) {
+				const value = this.toValue(this.get(valuePath, item));
+				if (value === undefined) {
+					return '';
+				}
+				if (value === null) {
+					return 'Invalid Date';
+				}
+				return this.renderValue(value, formatter);
 			}
-			return localISOString;
-		}
 
-		/**
-		 * Calculates the local timezone offset and formats it to ISO Timezone string.
-		 * @param  {String} localISOString an ISO date string
-		 * @return {String}                the ISO timezone
-		 */
-		_getTimezoneString(localISOString) {
-			const off = -new Date(localISOString).getTimezoneOffset() / 60;
-			return (off < 0 ? '-' : '+') + ['0', Math.abs(off)].join('').substr(-2) + ':00';
-		}
+			/**
+			* Computes the local timezone and adds it to a local ISO string
+			* @param  {String} localISOString an ISO date string, without timezone info
+			* @return {String}                an ISO date string, with timezone info
+			*/
+			getAbsoluteISOString(localISOString) {
+				// Most browsers use local timezone when no timezone is specified
+				// but Safari uses UTC, so we set it implicitly
+				// TODO: Consider removing this when/if Safari handles local timezone correctly
+				if (localISOString.length === 19) {
+					return localISOString + this._getTimezoneString(localISOString);
+				}
+				return localISOString;
+			}
 
-		renderValue(value, formatter = this.formatter) {
-			if (formatter == null) {
-				return;
+			/**
+			 * Calculates the local timezone offset and formats it to ISO Timezone string.
+			 * @param  {String} localISOString an ISO date string
+			 * @return {String}                the ISO timezone
+			 */
+			_getTimezoneString(localISOString) {
+				const off = -new Date(localISOString).getTimezoneOffset() / 60;
+				return (off < 0 ? '-' : '+') + ['0', Math.abs(off)].join('').substr(-2) + ':00';
 			}
-			const date = this.toValue(value);
-			if (date == null) {
-				return;
+
+			renderValue(value, formatter = this.formatter) {
+				if (formatter == null) {
+					return;
+				}
+				const date = this.toValue(value);
+				if (date == null) {
+					return;
+				}
+				return formatter.format(date);
 			}
-			return formatter.format(date);
-		}
 
-		_computeFormatter(locale) {
-			return new Intl.DateTimeFormat(locale || undefined);
-		}
+			_computeFormatter(locale) {
+				return new Intl.DateTimeFormat(locale || undefined);
+			}
 
-		_toInputString(value) {
-			const date = this.toValue(value);
-			if (date == null) {
-				return null;
+			_toInputString(value) {
+				const date = this.toValue(value);
+				if (date == null) {
+					return null;
+				}
+				return this._toLocalISOString(date).slice(0, 10);
 			}
-			return this._toLocalISOString(date).slice(0, 10);
-		}
 
-		_dateValueChanged(event) {
-			const input = event.currentTarget,
-				value = input.value,
-				item = event.model.item,
-				oldValue = this.get(this.valuePath, item),
-				date = this._fromInputString(value);
-			if (date == null) {
-				return;
+			_dateValueChanged(event) {
+				const input = event.currentTarget,
+					value = input.value,
+					item = event.model.item,
+					oldValue = this.get(this.valuePath, item),
+					date = this._fromInputString(value);
+				if (date == null) {
+					return;
+				}
+				this.set(this.valuePath, date, item);
+				this._fireItemChangeEvent(item, this.valuePath, oldValue, this.renderValue.bind(this));
 			}
-			this.set(this.valuePath, date, item);
-			this._fireItemChangeEvent(item, this.valuePath, oldValue, this.renderValue.bind(this));
-		}
 
-		_toLocalISOString(date) {
-			if (!(date instanceof Date)) {
-				return null;
+			_toLocalISOString(date) {
+				return toLocalISOString(date);
 			}
-			const pad = number => number < 10 ? '0' + number : number;
-			return date.getFullYear() +
-				'-' + pad(date.getMonth() + 1) +
-				'-' + pad(date.getDate()) +
-				'T' + pad(date.getHours()) +
-				':' + pad(date.getMinutes()) +
-				':' + pad(date.getSeconds()) +
-				'.' + (date.getMilliseconds() / 1000).toFixed(3).slice(2, 5);
 		}
-	}
-);
+	);
+
+	Cosmoz.DateColumnMixin.toLocalISOString = toLocalISOString;
+})();
 </script>