diff --git a/test/tests/customhighlights.js b/test/tests/customhighlights.js
new file mode 100644
index 00000000..7be921ea
--- /dev/null
+++ b/test/tests/customhighlights.js
@@ -0,0 +1,77 @@
+"use strict";
+
+const expect = require("chai").expect;
+
+const Client = require("../../src/client");
+
+const client = new Client({}, "test", {clientSettings: {highlights: "foo, @all,   sp ace   , 고"}});
+
+describe("Custom highlights", function() {
+	it("should NOT highlight", function() {
+		const teststrings = [
+			"and foos stuff",
+			"test foobar",
+			"testfoo bar",
+			"fooö",
+			"wtf@all",
+			"foo고",
+			"test고",
+			"space",
+			"sp:ace",
+		];
+
+		for (const teststring of teststrings) {
+			expect(teststring).to.not.match(client.highlightRegex);
+		}
+	});
+
+	it("should highlight", function() {
+		const teststrings = [
+			"Hey foo hello",
+			"hey Foo: hi",
+			"hey Foo, hi",
+			"<foo> testing",
+			"foo",
+			"hey @all test",
+			"testing foo's stuff",
+			"\"foo\"",
+			"\"@all\"",
+			"foo!",
+			"www.foo.bar",
+			"www.bar.foo/page",
+			"고",
+			"test 고",
+			"고!",
+			"www.고.com",
+			"hey @Foo",
+			"hey ~Foo",
+			"hey +Foo",
+			"hello &foo",
+			"@all",
+			"@all wtf",
+			"wtf @all",
+			"@@all",
+			"@고",
+			"f00 sp ace: bar",
+		];
+
+		for (const teststring of teststrings) {
+			expect(teststring).to.match(client.highlightRegex);
+		}
+	});
+
+	it("should trim custom highlights in the compiled regex", function() {
+		expect(client.highlightRegex).to.match(/\(\?:foo\|@all\|sp ace\|고\)/);
+	});
+
+	it("should NOT compile a regex", function() {
+		// test updating the regex and invalid custom hl inputs
+		client.config.clientSettings.highlights = ",,";
+		client.compileCustomHighlights();
+		expect(client.highlightRegex).to.be.null;
+
+		client.config.clientSettings.highlights = "  ";
+		client.compileCustomHighlights();
+		expect(client.highlightRegex).to.be.null;
+	});
+});