diff --git a/src/command/config/update.rs b/src/command/config/update.rs
index 38342a3..136c2aa 100644
--- a/src/command/config/update.rs
+++ b/src/command/config/update.rs
@@ -18,24 +18,26 @@ pub(crate) enum UpdateError {
     RevisionCheck(#[from] RevisionCheckError),
     #[error(transparent)]
     FileOperation(#[from] io::Error),
+    #[error("downgrading is not supported")]
+    Downgrade,
     #[error(transparent)]
     V1(#[from] v1::Error),
 }
 
 pub(super) async fn run(revision: Option<Revision>) -> Result<(), UpdateError> {
-    let current_revision = current_revision()?;
+    let current = current_revision()?;
 
-    if current_revision.next().is_none() {
+    if current.next().is_none() {
         println!("Your config files are already up-to-date! (as of this fishctl release)");
         return Ok(());
     }
-    if current_revision != Revision::V0 {
+    if current != Revision::V0 {
         take_backup()?;
     }
 
     match revision {
-        Some(revision) => update_to(revision).await,
-        None => update_to_latest_from(current_revision).await,
+        Some(target) => update(current, target).await,
+        None => update(current, Revision::last().unwrap()).await,
     }
 }
 
@@ -59,17 +61,22 @@ fn take_backup() -> Result<(), UpdateError> {
     Ok(())
 }
 
-async fn update_to_latest_from(mut current_revision: Revision) -> Result<(), UpdateError> {
-    while let Some(next_revision) = current_revision.next() {
-        update_to(next_revision.clone()).await?;
-        current_revision = next_revision;
+/// Updates config files to the specified revision.
+async fn update(mut current: Revision, target: Revision) -> Result<(), UpdateError> {
+    if current > target {
+        return Err(UpdateError::Downgrade);
+    }
+    while current < target {
+        let next = current.next().unwrap();
+        update_one_revision(next.clone()).await?;
+        current = next;
     }
     Ok(())
 }
 
-/// Updates config files to the specified revision.
-async fn update_to(revision: Revision) -> Result<(), UpdateError> {
-    match revision {
+/// Updates config file revision from `target - 1` to `target`.
+async fn update_one_revision(target: Revision) -> Result<(), UpdateError> {
+    match target {
         Revision::V0 => unreachable!(),
         Revision::V1 => v1::run().await?,
     }
diff --git a/src/config/mod.rs b/src/config/mod.rs
index 3438ff8..743e2c4 100644
--- a/src/config/mod.rs
+++ b/src/config/mod.rs
@@ -11,7 +11,9 @@ use validator::ValidationError;
 pub(crate) const SERVER_CONFIG_PATH: &str = "config/server.toml";
 pub(crate) const CLIENT_CONFIG_PATH: &str = "config/client.toml";
 
-#[derive(Deserialize_repr, Serialize_repr, PartialEq, Clone, ValueEnum, Sequence, Debug)]
+#[derive(
+    Deserialize_repr, Serialize_repr, PartialEq, PartialOrd, Clone, ValueEnum, Sequence, Debug,
+)]
 #[clap(rename_all = "lowercase")]
 #[repr(u8)]
 pub enum Revision {