diff --git a/public/language/en-GB/aria.json b/public/language/en-GB/aria.json
index 8e2c565c82..ec7889d2f4 100644
--- a/public/language/en-GB/aria.json
+++ b/public/language/en-GB/aria.json
@@ -5,5 +5,6 @@
 	"profile-page-for": "Profile page for user %1",
 	"user-watched-tags": "User watched tags",
 	"delete-upload-button": "Delete upload button",
-	"group-page-link-for": "Group page link for %1"
+	"group-page-link-for": "Group page link for %1",
+	"show-crossposts": "Show Cross-posts"
 }
\ No newline at end of file
diff --git a/public/language/en-GB/global.json b/public/language/en-GB/global.json
index 7e66953d0a..8c76edde4c 100644
--- a/public/language/en-GB/global.json
+++ b/public/language/en-GB/global.json
@@ -81,6 +81,7 @@
 	"users": "Users",
 	"topics": "Topics",
 	"posts": "Posts",
+	"crossposts": "Cross-posts",
 	"x-posts": "<span class=\"formatted-number\">%1</span> posts",
 	"x-topics": "<span class=\"formatted-number\">%1</span> topics",
 	"x-reputation": "<span class=\"formatted-number\">%1</span> reputation",
diff --git a/public/src/client/topic.js b/public/src/client/topic.js
index bdebc50264..97787e749e 100644
--- a/public/src/client/topic.js
+++ b/public/src/client/topic.js
@@ -69,6 +69,7 @@ define('forum/topic', [
 		setupQuickReply();
 		handleBookmark(tid);
 		handleThumbs();
+		addCrosspostsHandler();
 
 		$(window).on('scroll', utils.debounce(updateTopicTitle, 250));
 
@@ -406,6 +407,23 @@ define('forum/topic', [
 		});
 	}
 
+	function addCrosspostsHandler() {
+		const anchorEl = document.getElementById('show-crossposts');
+		if (anchorEl) {
+			anchorEl.addEventListener('click', async () => {
+				const { crossposts } = ajaxify.data;
+				const html = await app.parseAndTranslate('modals/crossposts', { crossposts });
+				bootbox.dialog({
+					size: 'sm',
+					onEscape: true,
+					backdrop: true,
+					title: '[[global:crossposts]]',
+					message: html,
+				});
+			});
+		}
+	}
+
 	function setupQuickReply() {
 		if (config.enableQuickReply || (config.theme && config.theme.enableQuickReply)) {
 			quickreply.init();
diff --git a/src/controllers/write/topics.js b/src/controllers/write/topics.js
index 2dea5dff5d..5bca992074 100644
--- a/src/controllers/write/topics.js
+++ b/src/controllers/write/topics.js
@@ -214,6 +214,11 @@ Topics.move = async (req, res) => {
 	helpers.formatApiResponse(200, res);
 };
 
+Topics.getCrossposts = async (req, res) => {
+	const crossposts = await topics.crossposts.get(req.params.tid);
+	helpers.formatApiResponse(200, res, { crossposts });
+};
+
 Topics.crosspost = async (req, res) => {
 	const { cid } = req.body;
 	const crossposts = await topics.crossposts.add(req.params.tid, cid, req.uid);
diff --git a/src/routes/write/topics.js b/src/routes/write/topics.js
index 0ec6fc2509..a1c7810558 100644
--- a/src/routes/write/topics.js
+++ b/src/routes/write/topics.js
@@ -54,6 +54,7 @@ module.exports = function () {
 
 	setupApiRoute(router, 'put', '/:tid/move', [...middlewares, middleware.assert.topic], controllers.write.topics.move);
 
+	setupApiRoute(router, 'get', '/:tid/crossposts', [...middlewares, middleware.assert.topic], controllers.write.topics.getCrossposts);
 	setupApiRoute(router, 'post', '/:tid/crossposts', [...middlewares, middleware.assert.topic], controllers.write.topics.crosspost);
 	setupApiRoute(router, 'delete', '/:tid/crossposts', [...middlewares, middleware.assert.topic], controllers.write.topics.uncrosspost);
 
diff --git a/src/topics/crossposts.js b/src/topics/crossposts.js
index ca07aadd7c..20ed086d71 100644
--- a/src/topics/crossposts.js
+++ b/src/topics/crossposts.js
@@ -17,7 +17,7 @@ Crossposts.get = async function (tid) {
 		return cids;
 	}, new Set());
 	let categoriesData = await categories.getCategoriesFields(
-		cids, ['cid', 'name', 'icon', 'bgColor', 'color', 'slug']
+		Array.from(cids), ['cid', 'name', 'icon', 'bgColor', 'color', 'slug']
 	);
 	categoriesData = categoriesData.reduce((map, category) => {
 		map.set(parseInt(category.cid, 10), category);