diff --git a/README.md b/README.md
index c7dac2d5..ba71fb35 100644
--- a/README.md
+++ b/README.md
@@ -97,16 +97,16 @@ steps:
 
 ## Inputs
 
-| Name                      | Required | Description                                                                                                                                                                          | Type   | Default  |
-| ------------------------- | -------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ | ------ | -------- |
-| `ocaml-compiler`          | Yes      | The OCaml compiler packages to initialise. Consult the [supported version syntax](#supported-version-syntax) section.                                                                | string |          |
-| `opam-repositories`       | No       | The name and URL pair of the repository to fetch the packages from.                                                                                                                  | string |          |
-| `opam-pin`                | No       | Enable the automation feature for opam pin.                                                                                                                                          | bool   | `true`   |
-| `opam-local-packages`     | No       | The local packages to be used by `opam-pin`. Consult the [`@actions/glob` documentation](https://github.com/actions/toolkit/tree/main/packages/glob) package for supported patterns. | string | `*.opam` |
-| `opam-disable-sandboxing` | No       | Disable the opam sandboxing feature.                                                                                                                                                 | bool   | `false`  |
-| `dune-cache`              | No       | Enable the dune cache feature. This feature **_requires_** dune 2.8.5 or later on the Windows runners.                                                                               | bool   | `false`  |
-| `cache-prefix`            | No       | The prefix of the cache keys.                                                                                                                                                        | string | `v1`     |
-| `allow-prerelease-opam`   | No       | Allow to use a pre-release version of opam.                                                                                                                                          | bool   | `false`  |
+| Name                      | Required | Description                                                                                                                                                                          | Type   | Default                                                 |
+| ------------------------- | -------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ | ------ | ------------------------------------------------------- |
+| `ocaml-compiler`          | Yes      | The OCaml compiler packages to initialise. Consult the [supported version syntax](#supported-version-syntax) section.                                                                | string |                                                         |
+| `opam-repositories`       | No       | The name and URL pair of the repository to fetch the packages from.                                                                                                                  | string | `default: https://github.com/ocaml/opam-repository.git` |
+| `opam-pin`                | No       | Enable the automation feature for opam pin.                                                                                                                                          | bool   | `true`                                                  |
+| `opam-local-packages`     | No       | The local packages to be used by `opam-pin`. Consult the [`@actions/glob` documentation](https://github.com/actions/toolkit/tree/main/packages/glob) package for supported patterns. | string | `*.opam`                                                |
+| `opam-disable-sandboxing` | No       | Disable the opam sandboxing feature.                                                                                                                                                 | bool   | `false`                                                 |
+| `dune-cache`              | No       | Enable the dune cache feature. This feature **_requires_** dune 2.8.5 or later on the Windows runners.                                                                               | bool   | `false`                                                 |
+| `cache-prefix`            | No       | The prefix of the cache keys.                                                                                                                                                        | string | `v1`                                                    |
+| `allow-prerelease-opam`   | No       | Allow to use a pre-release version of opam.                                                                                                                                          | bool   | `false`                                                 |
 
 ### Supported version syntax
 
diff --git a/action.yml b/action.yml
index d8ad08fe..e0ba3271 100644
--- a/action.yml
+++ b/action.yml
@@ -15,7 +15,8 @@ inputs:
   opam-repositories:
     description: The name and URL pair of the repository to fetch the packages from.
     required: false
-    default: ""
+    default: |
+      default: git+https://github.com/ocaml/opam-repository.git
   opam-pin:
     description: Enable the automation feature for opam pin.
     required: false
diff --git a/dist/index.js b/dist/index.js
index 0ab258e4..768cabf4 100644
--- a/dist/index.js
+++ b/dist/index.js
@@ -91992,9 +91992,7 @@ const OPAM_REPOSITORIES = (() => {
         required: false,
         trimWhitespace: true,
     }));
-    return repositories_yaml
-        ? Object.entries(repositories_yaml).reverse()
-        : [["default", "https://github.com/ocaml/opam-repository.git"]];
+    return Object.entries(repositories_yaml).reverse();
 })();
 
 ;// CONCATENATED MODULE: external "node:fs"
diff --git a/dist/post/index.js b/dist/post/index.js
index 625e9936..95b63493 100644
--- a/dist/post/index.js
+++ b/dist/post/index.js
@@ -84796,9 +84796,7 @@ const OPAM_REPOSITORIES = (() => {
         required: false,
         trimWhitespace: true,
     }));
-    return repositories_yaml
-        ? Object.entries(repositories_yaml).reverse()
-        : [["default", "https://github.com/ocaml/opam-repository.git"]];
+    return Object.entries(repositories_yaml).reverse();
 })();
 
 ;// CONCATENATED MODULE: ./src/cache.ts
diff --git a/packages/setup-ocaml/src/constants.ts b/packages/setup-ocaml/src/constants.ts
index 2537e928..b138c142 100644
--- a/packages/setup-ocaml/src/constants.ts
+++ b/packages/setup-ocaml/src/constants.ts
@@ -127,9 +127,6 @@ export const OPAM_REPOSITORIES: [string, string][] = (() => {
       required: false,
       trimWhitespace: true,
     }),
-  ) as Record<string, string> | null;
-
-  return repositories_yaml
-    ? Object.entries(repositories_yaml).reverse()
-    : [["default", "https://github.com/ocaml/opam-repository.git"]];
+  ) as Record<string, string>;
+  return Object.entries(repositories_yaml).reverse();
 })();