diff --git a/src/helper.js b/src/helper.js
index c34e16ac..052e4115 100644
--- a/src/helper.js
+++ b/src/helper.js
@@ -157,6 +157,8 @@ function ip2hex(address) {
 	}).join("");
 }
 
+// Expand ~ into the current user home dir.
+// This does *not* support `~other_user/tmp` => `/home/other_user/tmp`.
 function expandHome(shortenedPath) {
 	if (!shortenedPath) {
 		return "";
diff --git a/test/src/helperTest.js b/test/src/helperTest.js
new file mode 100644
index 00000000..36d1b518
--- /dev/null
+++ b/test/src/helperTest.js
@@ -0,0 +1,39 @@
+"use strict";
+
+const expect = require("chai").expect;
+const os = require("os");
+const Helper = require("../../src/helper");
+
+describe("Helper", function() {
+	describe("#expandHome", function() {
+		it("should correctly expand a Unix path", function() {
+			expect([`${os.homedir()}/tmp`, `${os.homedir()}\\tmp`])
+				.to.include(Helper.expandHome("~/tmp"));
+		});
+
+		it("should correctly expand a Windows path", function() {
+			expect(Helper.expandHome("~\\tmp")).to.equal(`${os.homedir()}\\tmp`);
+		});
+
+		it("should correctly expand when not given a specific path", function() {
+			expect(Helper.expandHome("~")).to.equal(os.homedir());
+		});
+
+		it("should not expand paths not starting with tilde", function() {
+			expect(Helper.expandHome("/tmp")).to.match(/^\/tmp|[A-Z]:\\tmp$/);
+		});
+
+		it("should not expand a tilde in the middle of a string", function() {
+			expect(Helper.expandHome("/tmp/~foo"))
+				.to.match(/^\/tmp\/~foo|[A-Z]:\\tmp\\~foo$/);
+		});
+
+		it("should return an empty string when given an empty string", function() {
+			expect(Helper.expandHome("")).to.equal("");
+		});
+
+		it("should return an empty string when given undefined", function() {
+			expect(Helper.expandHome(undefined)).to.equal("");
+		});
+	});
+});