diff --git a/src/main.js b/src/main.js
index 8d462ee..56035dc 100644
--- a/src/main.js
+++ b/src/main.js
@@ -2,4 +2,6 @@
   return a + b;
 }
 
-// TODO: subtraction
\ No newline at end of file
+export function subtract(a, b) {
+  return a - b;
+}
diff --git a/src/main.test.js b/src/main.test.js
index 7768201..aacdde3 100644
--- a/src/main.test.js
+++ b/src/main.test.js
@@ -1,7 +1,11 @@
-import { add } from "./main";
+import { add, subtract } from "./main";
 import { expect } from "@esm-bundle/chai";
 
 describe("main tests", () => {
+  it("subtracts two numbers", () => {
+    expect(subtract(3, 5)).to.equal(-2);
+  });
+
   it("adds two numbers", () => {
     expect(add(3, 5)).to.equal(8);
   });