diff --git a/src/packet.rs b/src/packet.rs
index 7e49e95..1aaf556 100644
--- a/src/packet.rs
+++ b/src/packet.rs
@@ -85,6 +85,11 @@ impl PacketWriter {
 		self.write_u8(b as u8)
 	}
 
+	/// writes a bool to the packet
+	fn write_bool(self, b: bool) -> Self {
+		self.write_u8(if b { 1 } else { 0 })
+	}
+
 	/// writes a u16 to the packet
 	fn write_u16(self, sh: u16) -> Self {
 		let mut s = self;
@@ -191,6 +196,11 @@ impl ExtBitmask {
 	fn info(self) -> Option<ExtInfo> {
 		// TODO: add entries as extensions are supported
 		Some(match self {
+			// this isn't actually used by the server at all, but it technically sort of implements it
+			Self::HeldBlock => ExtInfo::new("HeldBlock".to_string(), 1, Self::HeldBlock),
+			Self::EmoteFix => ExtInfo::new("EmoteFix".to_string(), 1, Self::EmoteFix),
+			// TODO: render CP437 properly in server output
+			Self::FullCP437 => ExtInfo::new("FullCP437".to_string(), 1, Self::FullCP437),
 			Self::EnvWeatherType => {
 				ExtInfo::new("EnvWeatherType".to_string(), 1, Self::EnvWeatherType)
 			}
diff --git a/src/packet/client.rs b/src/packet/client.rs
index 618438a..47b0d79 100644
--- a/src/packet/client.rs
+++ b/src/packet/client.rs
@@ -27,8 +27,8 @@ pub enum ClientPacket {
 	},
 	/// sent to update the player's current position and orientation with the server
 	PositionOrientation {
-		/// should always be 0xff (-1), referring to the player who sent it
-		_player_id: i8,
+		/// if the HeldBlock extension is supported, this should contain the block the player is currently holding
+		_player_id_or_held_block: i8,
 		x: f16,
 		y: f16,
 		z: f16,
@@ -78,7 +78,7 @@ impl ClientPacket {
 				block_type: buf.try_get_u8().ok()?,
 			},
 			0x08 => Self::PositionOrientation {
-				_player_id: buf.try_get_i8().ok()?,
+				_player_id_or_held_block: buf.try_get_i8().ok()?,
 				x: buf.try_get_f16().ok()?,
 				y: buf.try_get_f16().ok()?,
 				z: buf.try_get_f16().ok()?,
diff --git a/src/packet/server.rs b/src/packet/server.rs
index f24b719..d4d6e24 100644
--- a/src/packet/server.rs
+++ b/src/packet/server.rs
@@ -99,6 +99,8 @@ pub enum ServerPacket {
 	ExtInfo {},
 	/// packet to send info about an extension on the server
 	ExtEntry { ext_name: String, version: i32 },
+	/// packet to set a player's currently held block
+	HoldThis { block: u8, prevent_change: bool },
 	/// informs the client that it should update the current weather
 	EnvWeatherType { weather_type: WeatherType },
 }
@@ -125,6 +127,7 @@ impl ServerPacket {
 
 			Self::ExtInfo {} => 0x10,
 			Self::ExtEntry { .. } => 0x11,
+			Self::HoldThis { .. } => 0x14,
 			Self::EnvWeatherType { .. } => 0x1f,
 		}
 	}
@@ -242,6 +245,10 @@ impl ServerPacket {
 			Self::ExtEntry { ext_name, version } => {
 				writer.write_string(ext_name).write_i32(*version)
 			}
+			Self::HoldThis {
+				block,
+				prevent_change,
+			} => writer.write_u8(*block).write_bool(*prevent_change),
 			Self::EnvWeatherType { weather_type } => writer.write_u8(weather_type.into()),
 		}
 	}
diff --git a/src/server/network.rs b/src/server/network.rs
index 40728b4..fd51055 100644
--- a/src/server/network.rs
+++ b/src/server/network.rs
@@ -328,7 +328,7 @@ async fn handle_stream_inner(
 					}
 				}
 				ClientPacket::PositionOrientation {
-					_player_id: _,
+					_player_id_or_held_block: _,
 					x,
 					y,
 					z,