diff --git a/README.md b/README.md
index a1933e91..f5d91c9b 100644
--- a/README.md
+++ b/README.md
@@ -158,7 +158,7 @@ Support this project with a :star:
 |                  path                  |        `string`        | `false`  |         `'.'`         |                                                                                                                              Relative path under <br> `GITHUB_WORKSPACE` <br> to the repository                                                                                                                               |
 |      since\_last\_remote\_commit       |       `boolean`        | `false`  |        `false`        |       Use the last commit on the remote <br> branch as the `base_sha` <br> (Defaults to the last commit <br> on the target branch for Pull requests <br> or the previous commit <br> on the current branch <br> for push events). <br /> **NOTE:** This requires <br /> `fetch-depth: 0` <br /> with `actions/checkout@v3`        |
 |               quotepath                |       `boolean`        | `false`  |        `true`         |                                                                                                                                Output filenames completely verbatim by setting this to `false`                                                                                                                                |
-|             diff\_relative             |       `boolean`        | `false`  |                       |                                                                                                                       Exclude changes outside the current directory and show pathnames relative to it.                                                                                                                        |
+|             diff\_relative             |       `boolean`        | `false`  |                       |                                                                                                                       Exclude changes outside the current directory and show pathnames relative to it. **NOTE:** This requires you to specify the top level directory via the `path` input.                                                                                                                     |
 |               dir\_names               |       `boolean`        | `false`  |        `false`        |                                                                                        Output unique changed directories instead of filenames. <br> **NOTE:** This returns `.` for <br> changed files located in the root of the project.                                                                                         |
 |                  json                  |       `boolean`        | `false`  |        `false`        |                                                                                                                            Output changed files in JSON format which can be used for [matrix jobs](https://github.com/tj-actions/changed-files/blob/main/.github/workflows/manual-matrix-test.yml).                                                                                                                             |
 |                  since                  |       `string`        | `false`  |                |                                                                                                                            Get changed files for commits whose timestamp is older than the given time.                                                                                                                             |