diff --git a/CHANGELOG.md b/CHANGELOG.md
index 7070990..92d86f3 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -8,6 +8,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 ### Fixed
 - `auto_trim` plugin: Trim comments.
 - `set` evaluates the expression twice.
+- `for`: Make sure key values of an array are always numbers [#83].
 
 ## [1.12.11] - 2024-11-03
 ### Fixed
@@ -264,6 +265,7 @@ First version
 [#72]: https://github.com/oscarotero/vento/issues/72
 [#73]: https://github.com/oscarotero/vento/issues/73
 [#74]: https://github.com/oscarotero/vento/issues/74
+[#83]: https://github.com/oscarotero/vento/issues/83
 
 [1.12.12]: https://github.com/oscarotero/vento/compare/v1.12.11...HEAD
 [1.12.11]: https://github.com/oscarotero/vento/compare/v1.12.10...v1.12.11
diff --git a/plugins/for.ts b/plugins/for.ts
index d2cce06..3b85d0b 100644
--- a/plugins/for.ts
+++ b/plugins/for.ts
@@ -59,7 +59,9 @@ function toIterator(
   }
 
   if (Array.isArray(item)) {
-    return withKeys ? Object.entries(item) : item;
+    return withKeys
+      ? Object.entries(item).map(([key, value]) => [parseInt(key, 10), value])
+      : item;
   }
 
   if (typeof item === "function") {
diff --git a/test/for.test.ts b/test/for.test.ts
index 1ec8465..bb76d88 100644
--- a/test/for.test.ts
+++ b/test/for.test.ts
@@ -46,6 +46,13 @@ Deno.test("For tag (array)", async () => {
     `,
     expected: "1(0)-2(1)-3(2)-4(3)-",
   });
+  // Fix for issue https://github.com/ventojs/vento/issues/83
+  await test({
+    template: `
+    {{ for key, name of [0, 1, 2, 3] }}{{key == name}}{{key === name}}{{ /for }}
+    `,
+    expected: "truetruetruetruetruetruetruetrue",
+  });
 });
 
 Deno.test("For tag (object)", async () => {
@@ -72,6 +79,27 @@ Deno.test("For tag (object)", async () => {
     `,
     expected: "1(one)-2(two)-",
   });
+
+  await test({
+    template: `
+    {{ for name of names }}{{people[name].surname}}{{ /for }}
+    `,
+    expected: "OteroRubio",
+    data: {
+      names: [
+        "Óscar",
+        "Laura",
+      ],
+      people: {
+        "Óscar": {
+          surname: "Otero",
+        },
+        "Laura": {
+          surname: "Rubio",
+        },
+      },
+    },
+  });
 });
 
 Deno.test("For tag (function)", async () => {