diff --git a/changelog/unreleased/pull-5162 b/changelog/unreleased/pull-5162
index 34c458486..6a0d75547 100644
--- a/changelog/unreleased/pull-5162
+++ b/changelog/unreleased/pull-5162
@@ -1,7 +1,8 @@
 Change: Promote feature flags
 
-The `explicit-s3-anonymous-auth` and `safe-forget-keep-tags` features are
-now stable and can no longer be disabled. These corresponding feature flags
+The `deprecate-legacy-index`, `deprecate-s3-legacy-layout`,
+`explicit-s3-anonymous-auth` and `safe-forget-keep-tags` features are
+now stable and can no longer be disabled. The corresponding feature flags
 will be removed in restic 0.19.0.
 
 https://github.com/restic/restic/pull/5162
diff --git a/internal/feature/registry.go b/internal/feature/registry.go
index 999797271..a7368fa75 100644
--- a/internal/feature/registry.go
+++ b/internal/feature/registry.go
@@ -6,6 +6,8 @@ var Flag = New()
 // flag names are written in kebab-case
 const (
 	BackendErrorRedesign    FlagName = "backend-error-redesign"
+	DeprecateLegacyIndex    FlagName = "deprecate-legacy-index"
+	DeprecateS3LegacyLayout FlagName = "deprecate-s3-legacy-layout"
 	DeviceIDForHardlinks    FlagName = "device-id-for-hardlinks"
 	ExplicitS3AnonymousAuth FlagName = "explicit-s3-anonymous-auth"
 	SafeForgetKeepTags      FlagName = "safe-forget-keep-tags"
@@ -15,6 +17,8 @@ const (
 func init() {
 	Flag.SetFlags(map[FlagName]FlagDesc{
 		BackendErrorRedesign:    {Type: Beta, Description: "enforce timeouts for stuck HTTP requests and use new backend error handling design."},
+		DeprecateLegacyIndex:    {Type: Stable, Description: "disable support for index format used by restic 0.1.0. Use `restic repair index` to update the index if necessary."},
+		DeprecateS3LegacyLayout: {Type: Stable, Description: "disable support for S3 legacy layout used up to restic 0.7.0. Use restic 0.17.3 to migrate if necessary."},
 		DeviceIDForHardlinks:    {Type: Alpha, Description: "store deviceID only for hardlinks to reduce metadata changes for example when using btrfs subvolumes. Will be removed in a future restic version after repository format 3 is available"},
 		ExplicitS3AnonymousAuth: {Type: Stable, Description: "forbid anonymous S3 authentication unless `-o s3.unsafe-anonymous-auth=true` is set"},
 		SafeForgetKeepTags:      {Type: Stable, Description: "prevent deleting all snapshots if the tag passed to `forget --keep-tags tagname` does not exist"},