diff --git a/pdb-ui/src/main/resources/templates/main.html b/pdb-ui/src/main/resources/templates/main.html
index e752f2f..27c5275 100644
--- a/pdb-ui/src/main/resources/templates/main.html
+++ b/pdb-ui/src/main/resources/templates/main.html
@@ -34,7 +34,7 @@
 		<input type="number" id="search-limit-value" name="search-limit-value" min="1" max="1000" value="10"/>
 		
 		<label for="search-date-from">From Date:</label>
-		<input id="search-date-from" class="input_date" type="text" value="{{oldestValue}}">
+		<input id="search-date-from" class="input_date" type="text" value="{{oldestValue}}" required="required" pattern="\d{4}-(0[1-9]|1[0-2])-(0[1-9]|[1-2]\d|3[0-1]) [0-2]\d:[0-5]\d:[0-5]\d">
 		
 		<label for="search-date-range">Interval:</label>
 		<input id="search-date-range" type="text" list="ranges" required="required" value="1 week" pattern="\d+ (second|minute|hour|day|week|month)s?">