diff --git a/public/src/client/flags/list.js b/public/src/client/flags/list.js
index f2e15cedab..49238b377a 100644
--- a/public/src/client/flags/list.js
+++ b/public/src/client/flags/list.js
@@ -47,35 +47,60 @@ define('forum/flags/list', [
 
 	Flags.enableFilterForm = function () {
 		const $filtersEl = components.get('flags/filters');
+		if ($filtersEl && $filtersEl.get(0).nodeName !== 'FORM') {
+			// Harmony; update hidden form and submit on change
+			const filtersEl = $filtersEl.get(0);
+			const formEl = filtersEl.querySelector('form');
 
-		// Parse ajaxify data to set form values to reflect current filters
-		for (const filter in ajaxify.data.filters) {
-			if (ajaxify.data.filters.hasOwnProperty(filter)) {
-				$filtersEl.find('[name="' + filter + '"]').val(ajaxify.data.filters[filter]);
+			filtersEl.addEventListener('click', (e) => {
+				const subselector = e.target.closest('[data-value]');
+				if (!subselector) {
+					return;
+				}
+
+				const name = subselector.getAttribute('data-name');
+				const value = subselector.getAttribute('data-value');
+
+				formEl[name].value = value;
+
+				applyFilters(formEl);
+			});
+		} else {
+			// Persona; parse ajaxify data to set form values to reflect current filters
+			for (const filter in ajaxify.data.filters) {
+				if (ajaxify.data.filters.hasOwnProperty(filter)) {
+					$filtersEl.find('[name="' + filter + '"]').val(ajaxify.data.filters[filter]);
+				}
 			}
-		}
-		$filtersEl.find('[name="sort"]').val(ajaxify.data.sort);
+			$filtersEl.find('[name="sort"]').val(ajaxify.data.sort);
 
-		document.getElementById('apply-filters').addEventListener('click', function () {
-			const payload = $filtersEl.serializeArray();
-			// cid is special comes from categoryFilter module
-			selectedCids.forEach(function (cid) {
-				payload.push({ name: 'cid', value: cid });
+			document.getElementById('apply-filters').addEventListener('click', function () {
+				applyFilters($filtersEl.get(0));
 			});
 
-			ajaxify.go('flags?' + (payload.length ? $.param(payload) : 'reset=1'));
-		});
-
-		$filtersEl.find('button[data-target="#more-filters"]').click((ev) => {
-			const textVariant = ev.target.getAttribute('data-text-variant');
-			if (!textVariant) {
-				return;
-			}
-			ev.target.setAttribute('data-text-variant', ev.target.textContent);
-			ev.target.firstChild.textContent = textVariant;
-		});
+			$filtersEl.find('button[data-target="#more-filters"]').click((ev) => {
+				const textVariant = ev.target.getAttribute('data-text-variant');
+				if (!textVariant) {
+					return;
+				}
+				ev.target.setAttribute('data-text-variant', ev.target.textContent);
+				ev.target.firstChild.textContent = textVariant;
+			});
+		}
 	};
 
+	function applyFilters(formEl) {
+		const payload = new FormData(formEl);
+		// cid is special comes from categoryFilter module
+		selectedCids.forEach(function (cid) {
+			payload.append('cid', cid);
+		});
+		const length = Array.from(payload.values()).filter(Boolean);
+		const qs = new URLSearchParams(payload).toString();
+
+		ajaxify.go('flags?' + (length ? qs : 'reset=1'));
+	}
+
 	Flags.enableCheckboxes = function () {
 		const flagsList = document.querySelector('[component="flags/list"]');
 		const checkboxes = flagsList.querySelectorAll('[data-flag-id] input[type="checkbox"]');