diff --git a/src/compiler/code_generator.ts b/src/compiler/code_generator.ts
index 3343b405..7b55f8ef 100644
--- a/src/compiler/code_generator.ts
+++ b/src/compiler/code_generator.ts
@@ -877,9 +877,9 @@ export class CodeGenerator {
       // Throw error on duplicate keys in dev mode
       this.helpers.add("OwlError");
       this.addLine(
-        `if (keys${block.id}.has(key${this.target.loopLevel})) { throw new OwlError(\`Got duplicate key in t-foreach: \${key${this.target.loopLevel}}\`)}`
+        `if (keys${block.id}.has(String(key${this.target.loopLevel}))) { throw new OwlError(\`Got duplicate key in t-foreach: \${key${this.target.loopLevel}}\`)}`
       );
-      this.addLine(`keys${block.id}.add(key${this.target.loopLevel});`);
+      this.addLine(`keys${block.id}.add(String(key${this.target.loopLevel}));`);
     }
     let id: string;
     if (ast.memo) {
diff --git a/tests/components/__snapshots__/t_foreach.test.ts.snap b/tests/components/__snapshots__/t_foreach.test.ts.snap
index 34c3f1df..665eeaec 100644
--- a/tests/components/__snapshots__/t_foreach.test.ts.snap
+++ b/tests/components/__snapshots__/t_foreach.test.ts.snap
@@ -53,8 +53,8 @@ exports[`list of components crash on duplicate key in dev mode 1`] = `
     for (let i1 = 0; i1 < l_block1; i1++) {
       ctx[\`item\`] = v_block1[i1];
       const key1 = 'child';
-      if (keys1.has(key1)) { throw new OwlError(\`Got duplicate key in t-foreach: \${key1}\`)}
-      keys1.add(key1);
+      if (keys1.has(String(key1))) { throw new OwlError(\`Got duplicate key in t-foreach: \${key1}\`)}
+      keys1.add(String(key1));
       const props1 = {};
       helpers.validateProps(\`Child\`, props1, this);
       c_block1[i1] = withKey(comp1(props1, key + \`__1__\${key1}\`, node, this, null), key1);
@@ -75,6 +75,42 @@ exports[`list of components crash on duplicate key in dev mode 2`] = `
 }"
 `;
 
+exports[`list of components crash when using object as keys that serialize to the same string 1`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  let { prepareList, OwlError, withKey } = helpers;
+  const comp1 = app.createComponent(\`Child\`, true, false, false, true);
+  
+  return function template(ctx, node, key = \\"\\") {
+    ctx = Object.create(ctx);
+    const [k_block1, v_block1, l_block1, c_block1] = prepareList([{},{}]);;
+    const keys1 = new Set();
+    for (let i1 = 0; i1 < l_block1; i1++) {
+      ctx[\`item\`] = v_block1[i1];
+      const key1 = ctx['item'];
+      if (keys1.has(String(key1))) { throw new OwlError(\`Got duplicate key in t-foreach: \${key1}\`)}
+      keys1.add(String(key1));
+      const props1 = {};
+      helpers.validateProps(\`Child\`, props1, this);
+      c_block1[i1] = withKey(comp1(props1, key + \`__1__\${key1}\`, node, this, null), key1);
+    }
+    return list(c_block1);
+  }
+}"
+`;
+
+exports[`list of components crash when using object as keys that serialize to the same string 2`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  
+  return function template(ctx, node, key = \\"\\") {
+    return text(\`\`);
+  }
+}"
+`;
+
 exports[`list of components list of sub components inside other nodes 1`] = `
 "function anonymous(app, bdom, helpers
 ) {
diff --git a/tests/components/t_foreach.test.ts b/tests/components/t_foreach.test.ts
index 197a516b..f809fc97 100644
--- a/tests/components/t_foreach.test.ts
+++ b/tests/components/t_foreach.test.ts
@@ -331,4 +331,32 @@ describe("list of components", () => {
     console.info = consoleInfo;
     expect(mockConsoleWarn).toBeCalledTimes(1);
   });
+
+  test("crash when using object as keys that serialize to the same string", async () => {
+    const consoleInfo = console.info;
+    console.info = jest.fn();
+    class Child extends Component {
+      static template = xml``;
+    }
+
+    class Parent extends Component {
+      static template = xml`
+        <t t-foreach="[{}, {}]" t-as="item" t-key="item">
+          <Child/>
+        </t>
+      `;
+      static components = { Child };
+    }
+
+    const app = new App(Parent, { test: true });
+    const mountProm = expect(app.mount(fixture)).rejects.toThrow(
+      "Got duplicate key in t-foreach: [object Object]"
+    );
+    await expect(nextAppError(app)).resolves.toThrow(
+      "Got duplicate key in t-foreach: [object Object]"
+    );
+    await mountProm;
+    console.info = consoleInfo;
+    expect(mockConsoleWarn).toBeCalledTimes(1);
+  });
 });