diff --git a/src/routes/activitypub/inbox.rs b/src/routes/activitypub/inbox.rs
index 921f7c2b..24ed4237 100644
--- a/src/routes/activitypub/inbox.rs
+++ b/src/routes/activitypub/inbox.rs
@@ -1,4 +1,4 @@
-use apb::{server::Inbox, ActivityType, Base, BaseType, ObjectType};
+use apb::{server::Inbox, Activity, ActivityType, Base, BaseType, ObjectType};
 use axum::{extract::{Query, State}, http::StatusCode, Json};
 use sea_orm::{Order, QueryFilter, QueryOrder, QuerySelect};
 
@@ -52,48 +52,27 @@ pub async fn post(
 		Identity::Local(_user) => return Err(UpubError::forbidden()),
 		Identity::Anonymous => return Err(UpubError::unauthorized()),
 	}
-	match activity.base_type() {
-		None => { Err(StatusCode::BAD_REQUEST.into()) },
 
-		Some(BaseType::Link(_x)) => {
-			tracing::warn!("skipping remote activity: {}", serde_json::to_string_pretty(&activity).unwrap());
-			Err(StatusCode::UNPROCESSABLE_ENTITY.into()) // we could but not yet
-		},
-
-		Some(BaseType::Object(ObjectType::Activity(ActivityType::Activity))) => {
+	// TODO we could process Links and bare Objects maybe, but probably out of AP spec?
+	match activity.activity_type().ok_or_else(UpubError::bad_request)? {
+		ActivityType::Activity => {
 			tracing::warn!("skipping unprocessable base activity: {}", serde_json::to_string_pretty(&activity).unwrap());
 			Err(StatusCode::UNPROCESSABLE_ENTITY.into()) // won't ingest useless stuff
 		},
 
-		Some(BaseType::Object(ObjectType::Activity(ActivityType::Delete))) =>
-			Ok(ctx.delete(activity).await?),
+		ActivityType::Delete => Ok(ctx.delete(activity).await?),
+		ActivityType::Follow => Ok(ctx.follow(activity).await?),
+		ActivityType::Accept(_) => Ok(ctx.accept(activity).await?),
+		ActivityType::Reject(_) => Ok(ctx.reject(activity).await?),
+		ActivityType::Like => Ok(ctx.like(activity).await?),
+		ActivityType::Create => Ok(ctx.create(activity).await?),
+		ActivityType::Update => Ok(ctx.update(activity).await?),
+		ActivityType::Undo => Ok(ctx.undo(activity).await?),
+		// ActivityType::Announce => Ok(ctx.announce(activity).await?),
 
-		Some(BaseType::Object(ObjectType::Activity(ActivityType::Follow))) =>
-			Ok(ctx.follow(activity).await?),
-
-		Some(BaseType::Object(ObjectType::Activity(ActivityType::Accept(_)))) =>
-			Ok(ctx.accept(activity).await?),
-
-		Some(BaseType::Object(ObjectType::Activity(ActivityType::Reject(_)))) =>
-			Ok(ctx.reject(activity).await?),
-
-		Some(BaseType::Object(ObjectType::Activity(ActivityType::Like))) =>
-			Ok(ctx.like(activity).await?),
-
-		Some(BaseType::Object(ObjectType::Activity(ActivityType::Create))) =>
-			Ok(ctx.create(activity).await?),
-
-		Some(BaseType::Object(ObjectType::Activity(ActivityType::Update))) =>
-			Ok(ctx.update(activity).await?),
-
-		Some(BaseType::Object(ObjectType::Activity(_x))) => {
+		_x => {
 			tracing::info!("received unimplemented activity on inbox: {}", serde_json::to_string_pretty(&activity).unwrap());
 			Err(StatusCode::NOT_IMPLEMENTED.into())
 		},
-
-		Some(_x) => {
-			tracing::warn!("ignoring non-activity object in inbox: {}", serde_json::to_string_pretty(&activity).unwrap());
-			Err(StatusCode::UNPROCESSABLE_ENTITY.into())
-		}
 	}
 }
diff --git a/src/server/inbox.rs b/src/server/inbox.rs
index 4416abbd..96718172 100644
--- a/src/server/inbox.rs
+++ b/src/server/inbox.rs
@@ -1,5 +1,6 @@
 use apb::{target::Addressed, Activity, Base, Object};
-use sea_orm::{sea_query::Expr, ColumnTrait, EntityTrait, IntoActiveModel, QueryFilter, Set};
+use reqwest::StatusCode;
+use sea_orm::{sea_query::Expr, ColumnTrait, Condition, EntityTrait, IntoActiveModel, QueryFilter, Set};
 
 use crate::{errors::{LoggableError, UpubError}, model};
 
@@ -181,7 +182,48 @@ impl apb::server::Inbox for Context {
 		Ok(())
 	}
 
-	async fn undo(&self, _activity: serde_json::Value) -> crate::Result<()> {
-		todo!()
+	async fn undo(&self, activity: serde_json::Value) -> crate::Result<()> {
+		let uid = activity.actor().id().ok_or_else(UpubError::bad_request)?;
+		// TODO in theory we could work with just object_id but right now only accept embedded
+		let undone_activity = activity.object().extract().ok_or_else(UpubError::bad_request)?;
+		let undone_aid = undone_activity.id().ok_or_else(UpubError::bad_request)?;
+		let undone_object_id = undone_activity.object().id().ok_or_else(UpubError::bad_request)?;
+		let activity_type = undone_activity.activity_type().ok_or_else(UpubError::bad_request)?;
+
+		match activity_type {
+			apb::ActivityType::Like => {
+				model::like::Entity::delete_many()
+					.filter(
+						Condition::all()
+							.add(model::like::Column::Actor.eq(&uid))
+							.add(model::like::Column::Likes.eq(&undone_object_id))
+					)
+					.exec(self.db())
+					.await?;
+				model::object::Entity::update_many()
+					.filter(model::object::Column::Id.eq(&undone_object_id))
+					.col_expr(model::object::Column::Likes, Expr::col(model::object::Column::Likes).sub(1))
+					.exec(self.db())
+					.await?;
+			},
+			apb::ActivityType::Follow => {
+				model::relation::Entity::delete_many()
+					.filter(
+						Condition::all()
+							.add(model::relation::Column::Follower.eq(&uid))
+							.add(model::relation::Column::Following.eq(&undone_object_id))
+					)
+					.exec(self.db())
+					.await?;
+			},
+			_ => {
+				tracing::error!("received 'Undo' for unimplemented activity: {}", serde_json::to_string_pretty(&activity).unwrap());
+				return Err(StatusCode::NOT_IMPLEMENTED.into());
+			},
+		}
+
+		model::activity::Entity::delete_by_id(undone_aid).exec(self.db()).await?;
+
+		Ok(())
 	}
 }