diff --git a/src/controllers/mods.js b/src/controllers/mods.js
index 52403a5950..ece6442889 100644
--- a/src/controllers/mods.js
+++ b/src/controllers/mods.js
@@ -76,27 +76,7 @@ modsController.flags.list = function (req, res, next) {
 			}, next);
 		},
 		function (data) {
-			// If res.locals.cids is populated, then slim down the categories list
-			if (res.locals.cids) {
-				data.categories = data.categories.filter(function (category) {
-					return res.locals.cids.indexOf(String(category.cid)) !== -1;
-				});
-			}
-
-			// Minimal returned set for templates.js
-			data.categories = data.categories.reduce(function (memo, cur) {
-				if (!res.locals.cids) {
-					memo[cur.cid] = cur.name;
-					return memo;
-				}
-
-				// If mod, remove categories they can't moderate
-				if (res.locals.cids.indexOf(String(cur.cid)) !== -1) {
-					memo[cur.cid] = cur.name;
-				}
-
-				return memo;
-			}, {});
+			data.categories = filterCategories(res.locals.cids, data.categories);
 
 			res.render('flags/list', {
 				flags: data.flags.flags,
@@ -117,6 +97,7 @@ modsController.flags.detail = function (req, res, next) {
 		moderatedCids: async.apply(user.getModeratedCids, req.uid),
 		flagData: async.apply(flags.get, req.params.flagId),
 		assignees: async.apply(user.getAdminsandGlobalModsandModerators),
+		categories: async.apply(categories.buildForSelect, req.uid, 'read'),
 	}, function (err, results) {
 		if (err || !results.flagData) {
 			return next(err || new Error('[[error:invalid-data]]'));
@@ -124,6 +105,12 @@ modsController.flags.detail = function (req, res, next) {
 			return next(new Error('[[error:no-privileges]]'));
 		}
 
+		if (!results.isAdminOrGlobalMod && results.moderatedCids.length) {
+			res.locals.cids = results.moderatedCids;
+		}
+
+		results.categories = filterCategories(res.locals.cids, results.categories);
+
 		if (results.flagData.type === 'user') {
 			results.flagData.type_path = 'uid';
 		} else if (results.flagData.type === 'post') {
@@ -142,10 +129,34 @@ modsController.flags.detail = function (req, res, next) {
 				return memo;
 			}, {}),
 			title: '[[pages:flag-details, ' + req.params.flagId + ']]',
+			categories: results.categories,
 		}));
 	});
 };
 
+function filterCategories(moderatedCids, categories) {
+	// If cids is populated, then slim down the categories list
+	if (moderatedCids) {
+		categories = categories.filter(function (category) {
+			return moderatedCids.includes(String(category.cid));
+		});
+	}
+
+	return categories.reduce(function (memo, cur) {
+		if (!moderatedCids) {
+			memo[cur.cid] = cur.name;
+			return memo;
+		}
+
+		// If mod, remove categories they can't moderate
+		if (moderatedCids.includes(String(cur.cid))) {
+			memo[cur.cid] = cur.name;
+		}
+
+		return memo;
+	}, {});
+}
+
 modsController.postQueue = function (req, res, next) {
 	async.waterfall([
 		function (next) {