diff --git a/public/src/utils.js b/public/src/utils.js
index 8f2dcb8e87..f1154b64e9 100644
--- a/public/src/utils.js
+++ b/public/src/utils.js
@@ -405,9 +405,13 @@
 					(relative_path.length > 0 ? targetLocation.pathname.indexOf(relative_path) === 0 : true)	// Subfolder installs need this additional check
 				);
 		},
+
+		rtrim: function (str) {
+			return str.replace(/\s+$/g, '');
+		},
 	};
 
-		/* eslint "no-extend-native": "off" */
+	/* eslint "no-extend-native": "off" */
 	if (typeof String.prototype.startsWith !== 'function') {
 		String.prototype.startsWith = function (prefix) {
 			if (this.length < prefix.length) {
@@ -429,9 +433,11 @@
 		};
 	}
 
+	// DEPRECATED: remove in 1.6
 	if (typeof String.prototype.rtrim !== 'function') {
 		String.prototype.rtrim = function () {
-			return this.replace(/\s+$/g, '');
+			console.warn('[deprecated] `String.prototype.rtrim` is deprecated as of NodeBB v1.5; use `utils.rtrim` instead.');
+			return utils.rtrim(this);
 		};
 	}
 
diff --git a/src/topics/create.js b/src/topics/create.js
index 2ec75d3781..f7ee2e326e 100644
--- a/src/topics/create.js
+++ b/src/topics/create.js
@@ -88,10 +88,6 @@ module.exports = function (Topics) {
 		], callback);
 	};
 
-	function rtrim(str) {
-		return str.replace(/\s+$/g, '');
-	}
-
 	Topics.post = function (data, callback) {
 		var uid = data.uid;
 		data.title = String(data.title).trim();
@@ -106,7 +102,7 @@ module.exports = function (Topics) {
 			},
 			function (next) {
 				if (data.content) {
-					data.content = rtrim(data.content);
+					data.content = utils.rtrim(data.content);
 				}
 				check(data.content, meta.config.minimumPostLength, meta.config.maximumPostLength, 'content-too-short', 'content-too-long', next);
 			},
@@ -239,7 +235,7 @@ module.exports = function (Topics) {
 			function (filteredData, next) {
 				content = filteredData.content || data.content;
 				if (content) {
-					content = rtrim(content);
+					content = utils.rtrim(content);
 				}
 
 				check(content, meta.config.minimumPostLength, meta.config.maximumPostLength, 'content-too-short', 'content-too-long', next);
diff --git a/test/utils.js b/test/utils.js
index 2beedcf3eb..9c8c2bfb12 100644
--- a/test/utils.js
+++ b/test/utils.js
@@ -171,4 +171,11 @@ describe('Utility Methods', function () {
 		}
 		done();
 	});
+
+	it('`utils.rtrim` should remove trailing space', function (done) {
+		assert.strictEqual(utils.rtrim('  thing   '), '  thing');
+		assert.strictEqual(utils.rtrim('\tthing\t\t'), '\tthing');
+		assert.strictEqual(utils.rtrim('\t thing \t'), '\t thing');
+		done();
+	});
 });