diff --git a/bundles/org.openhab.ui.basic/web-src/smarthome.js b/bundles/org.openhab.ui.basic/web-src/smarthome.js
index 01a76712a6..414b4b31cb 100644
--- a/bundles/org.openhab.ui.basic/web-src/smarthome.js
+++ b/bundles/org.openhab.ui.basic/web-src/smarthome.js
@@ -1537,6 +1537,7 @@
 
 		var
 			lastValue = _t.input.value,
+			lastUndef = _t.input.nextElementSibling.innerHTML.trim(),
 			numberPattern = /^(\+|-)?[0-9\.,]+/,
 			timePattern = /^[0-9]{2}:[0-9]{2}/,
 			dotSeparatorPattern = /^-?(([0-9]{1,3}(,[0-9]{3})*)|([0-9]*))?(\.[0-9]+)?$/,
@@ -1624,25 +1625,41 @@
 		}
 
 		_t.setValuePrivate = function(value, itemState) {
-			var state = (itemState === "undefined" || itemState === "UNDEF" || itemState === "NULL") ? "" : itemState;
-
 			if (_t.verify) {
 				_t.verify.cancel();
 			}
 
-			var newValue = value ? value : state;
+			var newValue = value;
+			var undefValue = "";
+			if (itemState === undefined) {
+				undefValue = lastUndef;
+			} else if (itemState === "NULL" || itemState === "UNDEF") {
+				newValue = "";
+				undefValue = (value !== "") ? value : lastUndef;
+			}
+
 			if (_t.inputHint === "number") {
-				newValue = parseNumber(newValue).value;
-				var valueArray = newValue.trim().split(" ");
-				if (valueArray.length > 0) {
-					newValue = valueArray[0];
-				}
-				if (valueArray.length > 1) {
-					_t.input.parentNode.nextElementSibling.innerHTML = valueArray[1];
+				if (newValue !== "") {
+					newValue = parseNumber(newValue).value;
+					var valueArray = newValue.trim().split(" ");
+					if (valueArray.length > 0) {
+						newValue = valueArray[0];
+					}
+					if (valueArray.length > 1) {
+						_t.input.parentNode.nextElementSibling.innerHTML = valueArray[1];
+					}
+				} else {
+					var undefArray = undefValue.split(" ");
+					if (undefArray.length > 0) {
+						undefValue = undefArray[0];
+					}
 				}
 			} else if (_t.itemType === "datetime") {
 				if (_t.inputHint) {
-					newValue = state ? state : value;
+					newValue = (itemState !== undefined) ? itemState : value;
+					undefValue = "";
+				} else {
+					undefValue = "YYYY-MM-DD hh:mm:ss";
 				}
 				newValue = newValue.trim().split(".")[0];
 				if (_t.inputHint === "date") {
@@ -1655,6 +1672,7 @@
 				}
 			}
 			_t.input.value = newValue;
+			_t.input.nextElementSibling.innerHTML = undefValue;
 
 			_t.input.parentNode.MaterialTextfield.change();
 			_t.input.parentNode.MaterialTextfield.checkValidity();