diff --git a/README.md b/README.md
index 47bada3..4f82543 100644
--- a/README.md
+++ b/README.md
@@ -74,7 +74,7 @@ These must be committed since GitHub Actions runs them directly.
 | `path`                       | Files, directories, and wildcard patterns to cache                                                                                               | Yes      |                                                                              |
 | `key`                        | Explicit key for restoring and saving cache                                                                                                      | Yes      |                                                                              |
 | `restore-keys`               | Ordered list of prefix-matched keys for fallback                                                                                                 | No       |                                                                              |
-| `fallback-to-default-branch` | Automatically add a fallback restore key pointing to the default branch cache (S3 backend only). Disable if you want strict branch isolation.    | No       | `false`                                                                      |
+| `fallback-to-default-branch` | Automatically add a fallback restore key pointing to the default branch cache (S3 backend only). Disable if you want strict branch isolation.    | No       | `true`                                                                      |
 | `fallback-branch`            | Optional maintenance branch for fallback restore keys (pattern: `branch-*`, S3 backend only). If not set, the repository default branch is used. | No       |                                                                              |
 | `environment`                | Environment to use (dev or prod, S3 backend only)                                                                                                | No       | `prod`                                                                       |
 | `upload-chunk-size`          | Chunk size for large file uploads (bytes)                                                                                                        | No       |                                                                              |
diff --git a/action.yml b/action.yml
index dbab774..a2c8be0 100644
--- a/action.yml
+++ b/action.yml
@@ -34,7 +34,7 @@ inputs:
     description: >
       When enabled, automatically adds a fallback restore key pointing to the default branch cache.
       Only applies to the S3 backend.
-    default: 'false'
+    default: 'true'
   backend:
     description: >
       Force cache backend ('github' or 's3'). If not set, falls back to the CACHE_BACKEND environment variable if defined,