diff --git a/phpBB/assets/javascript/core.js b/phpBB/assets/javascript/core.js
index 4657af90ab..aa9dc9af82 100644
--- a/phpBB/assets/javascript/core.js
+++ b/phpBB/assets/javascript/core.js
@@ -431,14 +431,14 @@ phpbb.timezoneSwitchDate = function(keepSelection) {
 
 	if ($("#timezone > optgroup[label='" + $('#tz_date').val() + "'] > option").size() === 1) {
 		// If there is only one timezone for the selected date, we just select that automatically.
-		$("#timezone > optgroup[label='" + $('#tz_date').val() + "'] > option:first").attr('selected', true);
+		$("#timezone > optgroup[label='" + $('#tz_date').val() + "'] > option:first").prop('selected', true);
 		keepSelection = true;
 	}
 
 	if (typeof keepSelection !== 'undefined' && !keepSelection) {
 		var timezoneOptions = $('#timezone > optgroup option');
 		if (timezoneOptions.filter(':selected').length <= 0) {
-			timezoneOptions.filter(':first').attr('selected', true);
+			timezoneOptions.filter(':first').prop('selected', true);
 		}
 	}
 };
diff --git a/phpBB/styles/prosilver/template/ajax.js b/phpBB/styles/prosilver/template/ajax.js
index 1d70adc48d..43f6dee9a5 100644
--- a/phpBB/styles/prosilver/template/ajax.js
+++ b/phpBB/styles/prosilver/template/ajax.js
@@ -373,7 +373,7 @@ $('#quick-mod-select').change(function () {
 });
 
 $('#delete_permanent').click(function () {
-	if ($(this).attr('checked')) {
+	if ($(this).prop('checked')) {
 		$('#delete_reason').hide();
 	} else {
 		$('#delete_reason').show();
diff --git a/phpBB/styles/prosilver/template/ucp_notifications.html b/phpBB/styles/prosilver/template/ucp_notifications.html
index 6a711cfd30..2712e53034 100644
--- a/phpBB/styles/prosilver/template/ucp_notifications.html
+++ b/phpBB/styles/prosilver/template/ucp_notifications.html
@@ -115,7 +115,7 @@
 	<input type="hidden" name="form_time" value="{FORM_TIME}" />
 	{S_HIDDEN_FIELDS}
 	<input type="submit" name="submit" value="<!-- IF MODE == 'notification_options' -->{L_SUBMIT}<!-- ELSE -->{L_MARK_READ}<!-- ENDIF -->" class="button1" />
-	<div><a href="#" onclick="$('#ucp input:checkbox').attr('checked', true); return false;">{L_MARK_ALL}</a> &bull; <a href="#" onclick="$('#ucp input:checkbox').attr('checked', false); return false;">{L_UNMARK_ALL}</a></div>
+	<div><a href="#" onclick="$('#ucp input:checkbox').prop('checked', true); return false;">{L_MARK_ALL}</a> &bull; <a href="#" onclick="$('#ucp input:checkbox').prop('checked', false); return false;">{L_UNMARK_ALL}</a></div>
 	{S_FORM_TOKEN}
 </fieldset>
 <!-- ENDIF -->
diff --git a/phpBB/styles/subsilver2/template/ucp_notifications.html b/phpBB/styles/subsilver2/template/ucp_notifications.html
index a8b0d2b896..64e21ec4a6 100644
--- a/phpBB/styles/subsilver2/template/ucp_notifications.html
+++ b/phpBB/styles/subsilver2/template/ucp_notifications.html
@@ -131,7 +131,7 @@
 <!-- ENDIF -->
 
 <!-- IF .notifications -->
-<div class="gensmall" style="float: {S_CONTENT_FLOW_END}; padding-top: 2px;"><b><a href="#" onclick="$('#ucp input:checkbox').attr('checked', true); return false;">{L_MARK_ALL}</a> :: <a href="#" onclick="$('#ucp input:checkbox').attr('checked', false); return false;">{L_UNMARK_ALL}</a></b></div>
+<div class="gensmall" style="float: {S_CONTENT_FLOW_END}; padding-top: 2px;"><b><a href="#" onclick="$('#ucp input:checkbox').prop('checked', true); return false;">{L_MARK_ALL}</a> :: <a href="#" onclick="$('#ucp input:checkbox').prop('checked', false); return false;">{L_UNMARK_ALL}</a></b></div>
 <!-- ENDIF -->
 
 </form>