diff --git a/fuzz/fuzz_targets/client_initial.rs b/fuzz/fuzz_targets/client_initial.rs
index f018298961..8e982b37ce 100644
--- a/fuzz/fuzz_targets/client_initial.rs
+++ b/fuzz/fuzz_targets/client_initial.rs
@@ -24,7 +24,7 @@ fuzz_target!(|data: &[u8]| {
     let (aead, hp) = initial_aead_and_hp(d_cid, Role::Client);
     let (_, pn) = remove_header_protection(&hp, header, payload);
 
-    let mut payload_enc = Encoder::with_capacity(1200);
+    let mut payload_enc = Encoder::with_capacity(MIN_INITIAL_PACKET_SIZE);
     payload_enc.encode(data); // Add fuzzed data.
 
     // Make a new header with a 1 byte packet number length.
@@ -49,8 +49,8 @@ fuzz_target!(|data: &[u8]| {
         )
         .unwrap();
     assert_eq!(header_enc.len() + v.len(), ciphertext.len());
-    // Pad with zero to get up to 1200.
-    ciphertext.resize(1200, 0);
+    // Pad with zero to get up to MIN_INITIAL_PACKET_SIZE.
+    ciphertext.resize(MIN_INITIAL_PACKET_SIZE, 0);
 
     apply_header_protection(
         &hp,
diff --git a/fuzz/fuzz_targets/server_initial.rs b/fuzz/fuzz_targets/server_initial.rs
index f4bd5ec0b9..f264619fe7 100644
--- a/fuzz/fuzz_targets/server_initial.rs
+++ b/fuzz/fuzz_targets/server_initial.rs
@@ -30,7 +30,7 @@ fuzz_target!(|data: &[u8]| {
     let (aead, hp) = initial_aead_and_hp(d_cid, Role::Server);
     let (_, pn) = remove_header_protection(&hp, header, payload);
 
-    let mut payload_enc = Encoder::with_capacity(1200);
+    let mut payload_enc = Encoder::with_capacity(MIN_INITIAL_PACKET_SIZE);
     payload_enc.encode(data); // Add fuzzed data.
 
     // Make a new header with a 1 byte packet number length.
@@ -55,8 +55,8 @@ fuzz_target!(|data: &[u8]| {
         )
         .unwrap();
     assert_eq!(header_enc.len() + v.len(), ciphertext.len());
-    // Pad with zero to get up to 1200.
-    ciphertext.resize(1200, 0);
+    // Pad with zero to get up to MIN_INITIAL_PACKET_SIZE.
+    ciphertext.resize(MIN_INITIAL_PACKET_SIZE, 0);
 
     apply_header_protection(
         &hp,
diff --git a/neqo-http3/src/connection_client.rs b/neqo-http3/src/connection_client.rs
index 18e513e743..7ca5bdba05 100644
--- a/neqo-http3/src/connection_client.rs
+++ b/neqo-http3/src/connection_client.rs
@@ -1292,7 +1292,7 @@ mod tests {
     use neqo_qpack::{encoder::QPackEncoder, QpackSettings};
     use neqo_transport::{
         CloseReason, ConnectionEvent, ConnectionParameters, Output, State, StreamId, StreamType,
-        Version, RECV_BUFFER_SIZE, SEND_BUFFER_SIZE,
+        Version, MIN_INITIAL_PACKET_SIZE, RECV_BUFFER_SIZE, SEND_BUFFER_SIZE,
     };
     use test_fixture::{
         anti_replay, default_server_h3, fixture_init, new_server, now,
@@ -7157,8 +7157,9 @@ mod tests {
     #[test]
     fn priority_update_during_full_buffer() {
         // set a lower MAX_DATA on the server side to restrict the data the client can send
-        let (mut client, mut server) =
-            connect_with_connection_parameters(ConnectionParameters::default().max_data(1200));
+        let (mut client, mut server) = connect_with_connection_parameters(
+            ConnectionParameters::default().max_data(MIN_INITIAL_PACKET_SIZE.try_into().unwrap()),
+        );
 
         let request_stream_id = make_request_and_exchange_pkts(&mut client, &mut server, false);
         let data_writable = |e| matches!(e, Http3ClientEvent::DataWritable { .. });
diff --git a/neqo-http3/src/features/extended_connect/tests/webtransport/mod.rs b/neqo-http3/src/features/extended_connect/tests/webtransport/mod.rs
index 3753c3122d..42b14fca11 100644
--- a/neqo-http3/src/features/extended_connect/tests/webtransport/mod.rs
+++ b/neqo-http3/src/features/extended_connect/tests/webtransport/mod.rs
@@ -12,7 +12,7 @@ use std::{cell::RefCell, rc::Rc, time::Duration};
 
 use neqo_common::event::Provider;
 use neqo_crypto::AuthenticationStatus;
-use neqo_transport::{ConnectionParameters, StreamId, StreamType};
+use neqo_transport::{ConnectionParameters, StreamId, StreamType, MIN_INITIAL_PACKET_SIZE};
 use test_fixture::{
     anti_replay, fixture_init, now, CountingConnectionIdGenerator, DEFAULT_ADDR, DEFAULT_ALPN_H3,
     DEFAULT_KEYS, DEFAULT_SERVER_NAME,
@@ -25,7 +25,7 @@ use crate::{
     WebTransportServerEvent, WebTransportSessionAcceptAction,
 };
 
-const DATAGRAM_SIZE: u64 = 1200;
+const DATAGRAM_SIZE: u64 = MIN_INITIAL_PACKET_SIZE as u64;
 
 pub fn wt_default_parameters() -> Http3Parameters {
     Http3Parameters::default()
diff --git a/neqo-transport/src/connection/tests/datagram.rs b/neqo-transport/src/connection/tests/datagram.rs
index f1b64b3c8f..864f6e05b6 100644
--- a/neqo-transport/src/connection/tests/datagram.rs
+++ b/neqo-transport/src/connection/tests/datagram.rs
@@ -19,14 +19,14 @@ use crate::{
     packet::PacketBuilder,
     quic_datagrams::MAX_QUIC_DATAGRAM,
     send_stream::{RetransmissionPriority, TransmissionPriority},
-    CloseReason, Connection, ConnectionParameters, Error, StreamType,
+    CloseReason, Connection, ConnectionParameters, Error, StreamType, MIN_INITIAL_PACKET_SIZE,
 };
 
 const DATAGRAM_LEN_MTU: u64 = 1310;
 const DATA_MTU: &[u8] = &[1; 1310];
 const DATA_BIGGER_THAN_MTU: &[u8] = &[0; 2620];
-const DATAGRAM_LEN_SMALLER_THAN_MTU: u64 = 1200;
-const DATA_SMALLER_THAN_MTU: &[u8] = &[0; 1200];
+const DATAGRAM_LEN_SMALLER_THAN_MTU: u64 = MIN_INITIAL_PACKET_SIZE as u64;
+const DATA_SMALLER_THAN_MTU: &[u8] = &[0; MIN_INITIAL_PACKET_SIZE];
 const DATA_SMALLER_THAN_MTU_2: &[u8] = &[0; 600];
 const OUTGOING_QUEUE: usize = 2;
 
@@ -259,7 +259,9 @@ fn datagram_after_stream_data() {
 
     // Create a stream with normal priority and send some data.
     let stream_id = client.stream_create(StreamType::BiDi).unwrap();
-    client.stream_send(stream_id, &[6; 1200]).unwrap();
+    client
+        .stream_send(stream_id, &[6; MIN_INITIAL_PACKET_SIZE])
+        .unwrap();
 
     assert!(
         matches!(send_packet_and_get_server_event(&mut client, &mut server), ConnectionEvent::RecvStreamReadable { stream_id: s } if s == stream_id)
@@ -289,7 +291,9 @@ fn datagram_before_stream_data() {
             RetransmissionPriority::default(),
         )
         .unwrap();
-    client.stream_send(stream_id, &[6; 1200]).unwrap();
+    client
+        .stream_send(stream_id, &[6; MIN_INITIAL_PACKET_SIZE])
+        .unwrap();
 
     // Write a datagram.
     let dgram_sent = client.stats().frame_tx.datagram;
@@ -440,7 +444,7 @@ fn send_datagram(sender: &mut Connection, receiver: &mut Connection, data: &[u8]
 
 #[test]
 fn multiple_datagram_events() {
-    const DATA_SIZE: usize = 1200;
+    const DATA_SIZE: usize = MIN_INITIAL_PACKET_SIZE;
     const MAX_QUEUE: usize = 3;
     const FIRST_DATAGRAM: &[u8] = &[0; DATA_SIZE];
     const SECOND_DATAGRAM: &[u8] = &[1; DATA_SIZE];
@@ -486,7 +490,7 @@ fn multiple_datagram_events() {
 
 #[test]
 fn too_many_datagram_events() {
-    const DATA_SIZE: usize = 1200;
+    const DATA_SIZE: usize = MIN_INITIAL_PACKET_SIZE;
     const MAX_QUEUE: usize = 2;
     const FIRST_DATAGRAM: &[u8] = &[0; DATA_SIZE];
     const SECOND_DATAGRAM: &[u8] = &[1; DATA_SIZE];
diff --git a/neqo-transport/src/connection/tests/vn.rs b/neqo-transport/src/connection/tests/vn.rs
index 815868d78d..28f830cb3e 100644
--- a/neqo-transport/src/connection/tests/vn.rs
+++ b/neqo-transport/src/connection/tests/vn.rs
@@ -17,7 +17,7 @@ use super::{
 use crate::{
     packet::PACKET_BIT_LONG,
     tparams::{self, TransportParameter},
-    ConnectionParameters, Error, Version,
+    ConnectionParameters, Error, Version, MIN_INITIAL_PACKET_SIZE,
 };
 
 // The expected PTO duration after the first Initial is sent.
@@ -30,7 +30,7 @@ fn unknown_version() {
     mem::drop(client.process(None, now()).dgram());
 
     let mut unknown_version_packet = vec![0x80, 0x1a, 0x1a, 0x1a, 0x1a];
-    unknown_version_packet.resize(1200, 0x0);
+    unknown_version_packet.resize(MIN_INITIAL_PACKET_SIZE, 0x0);
     mem::drop(client.process(Some(&datagram(unknown_version_packet)), now()));
     assert_eq!(1, client.stats().dropped_rx);
 }
@@ -40,7 +40,7 @@ fn server_receive_unknown_first_packet() {
     let mut server = default_server();
 
     let mut unknown_version_packet = vec![0x80, 0x1a, 0x1a, 0x1a, 0x1a];
-    unknown_version_packet.resize(1200, 0x0);
+    unknown_version_packet.resize(MIN_INITIAL_PACKET_SIZE, 0x0);
 
     assert_eq!(
         server.process(Some(&datagram(unknown_version_packet,)), now(),),
diff --git a/neqo-transport/src/connection/tests/zerortt.rs b/neqo-transport/src/connection/tests/zerortt.rs
index b5e5f0d758..a34e5acdb2 100644
--- a/neqo-transport/src/connection/tests/zerortt.rs
+++ b/neqo-transport/src/connection/tests/zerortt.rs
@@ -14,7 +14,10 @@ use super::{
     super::Connection, connect, default_client, default_server, exchange_ticket, new_server,
     resumed_server, CountingConnectionIdGenerator,
 };
-use crate::{events::ConnectionEvent, ConnectionParameters, Error, StreamType, Version};
+use crate::{
+    events::ConnectionEvent, ConnectionParameters, Error, StreamType, Version,
+    MIN_INITIAL_PACKET_SIZE,
+};
 
 #[test]
 fn zero_rtt_negotiate() {
@@ -57,8 +60,8 @@ fn zero_rtt_send_recv() {
     client.stream_send(client_stream_id, &[1, 2, 3]).unwrap();
     let client_0rtt = client.process(None, now());
     assert!(client_0rtt.as_dgram_ref().is_some());
-    // 0-RTT packets on their own shouldn't be padded to 1200.
-    assert!(client_0rtt.as_dgram_ref().unwrap().len() < 1200);
+    // 0-RTT packets on their own shouldn't be padded to MIN_INITIAL_PACKET_SIZE.
+    assert!(client_0rtt.as_dgram_ref().unwrap().len() < MIN_INITIAL_PACKET_SIZE);
 
     let server_hs = server.process(client_hs.as_dgram_ref(), now());
     assert!(server_hs.as_dgram_ref().is_some()); // ServerHello, etc...
diff --git a/neqo-transport/src/lib.rs b/neqo-transport/src/lib.rs
index 723a86980e..54b08a9339 100644
--- a/neqo-transport/src/lib.rs
+++ b/neqo-transport/src/lib.rs
@@ -61,6 +61,7 @@ pub use self::{
     },
     events::{ConnectionEvent, ConnectionEvents},
     frame::CloseError,
+    packet::MIN_INITIAL_PACKET_SIZE,
     quic_datagrams::DatagramTracking,
     recv_stream::{RecvStreamStats, RECV_BUFFER_SIZE},
     send_stream::{SendStreamStats, SEND_BUFFER_SIZE},
diff --git a/neqo-transport/src/packet/mod.rs b/neqo-transport/src/packet/mod.rs
index 10d9b13208..1c38e8a94b 100644
--- a/neqo-transport/src/packet/mod.rs
+++ b/neqo-transport/src/packet/mod.rs
@@ -23,6 +23,10 @@ use crate::{
     Error, Res,
 };
 
+/// `MIN_INITIAL_PACKET_SIZE` is the smallest packet that can be used to establish
+/// a new connection across all QUIC versions this server supports.
+pub const MIN_INITIAL_PACKET_SIZE: usize = 1200;
+
 pub const PACKET_BIT_LONG: u8 = 0x80;
 const PACKET_BIT_SHORT: u8 = 0x00;
 const PACKET_BIT_FIXED_QUIC: u8 = 0x40;
diff --git a/neqo-transport/src/server.rs b/neqo-transport/src/server.rs
index 60909d71e1..bce87beb4d 100644
--- a/neqo-transport/src/server.rs
+++ b/neqo-transport/src/server.rs
@@ -33,7 +33,7 @@ use crate::{
     addr_valid::{AddressValidation, AddressValidationResult},
     cid::{ConnectionId, ConnectionIdDecoder, ConnectionIdGenerator, ConnectionIdRef},
     connection::{Connection, Output, State},
-    packet::{PacketBuilder, PacketType, PublicPacket},
+    packet::{PacketBuilder, PacketType, PublicPacket, MIN_INITIAL_PACKET_SIZE},
     ConnectionParameters, Res, Version,
 };
 
@@ -43,9 +43,6 @@ pub enum InitialResult {
     Retry(Vec<u8>),
 }
 
-/// `MIN_INITIAL_PACKET_SIZE` is the smallest packet that can be used to establish
-/// a new connection across all QUIC versions this server supports.
-const MIN_INITIAL_PACKET_SIZE: usize = 1200;
 /// The size of timer buckets.  This is higher than the actual timer granularity
 /// as this depends on there being some distribution of events.
 const TIMER_GRANULARITY: Duration = Duration::from_millis(4);
diff --git a/neqo-transport/src/tparams.rs b/neqo-transport/src/tparams.rs
index eada56cc4c..5161b69d6b 100644
--- a/neqo-transport/src/tparams.rs
+++ b/neqo-transport/src/tparams.rs
@@ -22,6 +22,7 @@ use neqo_crypto::{
 
 use crate::{
     cid::{ConnectionId, ConnectionIdEntry, CONNECTION_ID_SEQNO_PREFERRED, MAX_CONNECTION_ID_LEN},
+    packet::MIN_INITIAL_PACKET_SIZE,
     version::{Version, VersionConfig, WireVersion},
     Error, Res,
 };
@@ -278,7 +279,7 @@ impl TransportParameter {
             },
 
             MAX_UDP_PAYLOAD_SIZE => match d.decode_varint() {
-                Some(v) if v >= 1200 => Self::Integer(v),
+                Some(v) if v >= MIN_INITIAL_PACKET_SIZE.try_into()? => Self::Integer(v),
                 _ => return Err(Error::TransportParameterError),
             },
 
diff --git a/neqo-transport/tests/connection.rs b/neqo-transport/tests/connection.rs
index 3cc711f80b..f57684bec6 100644
--- a/neqo-transport/tests/connection.rs
+++ b/neqo-transport/tests/connection.rs
@@ -7,7 +7,9 @@
 mod common;
 
 use neqo_common::{Datagram, Decoder, Encoder, Role};
-use neqo_transport::{CloseReason, ConnectionParameters, Error, State, Version};
+use neqo_transport::{
+    CloseReason, ConnectionParameters, Error, State, Version, MIN_INITIAL_PACKET_SIZE,
+};
 use test_fixture::{
     default_client, default_server,
     header_protection::{
@@ -104,7 +106,7 @@ fn reorder_server_initial() {
 
     // And rebuild a packet.
     let mut packet = header.clone();
-    packet.resize(1200, 0);
+    packet.resize(MIN_INITIAL_PACKET_SIZE, 0);
     aead.encrypt(pn, &header, &plaintext, &mut packet[header.len()..])
         .unwrap();
     apply_header_protection(&hp, &mut packet, protected_header.len()..header.len());
@@ -237,7 +239,7 @@ fn overflow_crypto() {
         let plen = payload.len();
         payload.pad_to(plen + 1000, 44);
 
-        let mut packet = Encoder::with_capacity(1200);
+        let mut packet = Encoder::with_capacity(MIN_INITIAL_PACKET_SIZE);
         packet
             .encode_byte(0xc1) // Initial with packet number length of 2.
             .encode_uint(4, Version::Version1.wire_version())
@@ -254,7 +256,7 @@ fn overflow_crypto() {
         aead.encrypt(pn, &header, payload.as_ref(), &mut packet[header.len()..])
             .unwrap();
         apply_header_protection(&hp, &mut packet, pn_offset..(pn_offset + 2));
-        packet.resize(1200, 0); // Initial has to be 1200 bytes!
+        packet.resize(MIN_INITIAL_PACKET_SIZE, 0); // Initial has to be MIN_INITIAL_PACKET_SIZE bytes!
 
         let dgram = Datagram::new(
             server_initial.source(),
diff --git a/neqo-transport/tests/retry.rs b/neqo-transport/tests/retry.rs
index 3f95511c3e..07eee6635d 100644
--- a/neqo-transport/tests/retry.rs
+++ b/neqo-transport/tests/retry.rs
@@ -17,7 +17,9 @@ use std::{
 use common::{connected_server, default_server, generate_ticket};
 use neqo_common::{hex_with_len, qdebug, qtrace, Datagram, Encoder, Role};
 use neqo_crypto::AuthenticationStatus;
-use neqo_transport::{server::ValidateAddress, CloseReason, Error, State, StreamType};
+use neqo_transport::{
+    server::ValidateAddress, CloseReason, Error, State, StreamType, MIN_INITIAL_PACKET_SIZE,
+};
 use test_fixture::{
     assertions, datagram, default_client,
     header_protection::{
@@ -331,7 +333,7 @@ fn retry_after_pto() {
     // Let PTO fire on the client and then let it exhaust its PTO packets.
     now += Duration::from_secs(1);
     let pto = client.process(None, now).dgram();
-    assert!(pto.unwrap().len() >= 1200);
+    assert!(pto.unwrap().len() >= MIN_INITIAL_PACKET_SIZE);
     let cb = client.process(None, now).callback();
     assert_ne!(cb, Duration::new(0, 0));
 
@@ -339,7 +341,7 @@ fn retry_after_pto() {
     assertions::assert_retry(retry.as_ref().unwrap());
 
     let ci2 = client.process(retry.as_ref(), now).dgram();
-    assert!(ci2.unwrap().len() >= 1200);
+    assert!(ci2.unwrap().len() >= MIN_INITIAL_PACKET_SIZE);
 }
 
 #[test]
@@ -430,11 +432,11 @@ fn mitm_retry() {
     qtrace!("notoken_header={}", hex_with_len(&notoken_header));
 
     // Encrypt.
-    let mut notoken_packet = Encoder::with_capacity(1200)
+    let mut notoken_packet = Encoder::with_capacity(MIN_INITIAL_PACKET_SIZE)
         .encode(&notoken_header)
         .as_ref()
         .to_vec();
-    notoken_packet.resize_with(1200, u8::default);
+    notoken_packet.resize_with(MIN_INITIAL_PACKET_SIZE, u8::default);
     aead.encrypt(
         pn,
         &notoken_header,
@@ -443,7 +445,7 @@ fn mitm_retry() {
     )
     .unwrap();
     // Unlike with decryption, don't truncate.
-    // All 1200 bytes are needed to reach the minimum datagram size.
+    // All MIN_INITIAL_PACKET_SIZE bytes are needed to reach the minimum datagram size.
 
     apply_header_protection(&hp, &mut notoken_packet, pn_offset..(pn_offset + pn_len));
     qtrace!("packet={}", hex_with_len(&notoken_packet));
diff --git a/neqo-transport/tests/server.rs b/neqo-transport/tests/server.rs
index 4740d26ded..36a49a48cf 100644
--- a/neqo-transport/tests/server.rs
+++ b/neqo-transport/tests/server.rs
@@ -16,6 +16,7 @@ use neqo_crypto::{
 use neqo_transport::{
     server::{ActiveConnectionRef, Server, ValidateAddress},
     CloseReason, Connection, ConnectionParameters, Error, Output, State, StreamType, Version,
+    MIN_INITIAL_PACKET_SIZE,
 };
 use test_fixture::{
     assertions, datagram, default_client,
@@ -227,14 +228,14 @@ fn drop_non_initial() {
     let mut server = default_server();
 
     // This is big enough to look like an Initial, but it uses the Retry type.
-    let mut header = neqo_common::Encoder::with_capacity(1200);
+    let mut header = neqo_common::Encoder::with_capacity(MIN_INITIAL_PACKET_SIZE);
     header
         .encode_byte(0xfa)
         .encode_uint(4, Version::default().wire_version())
         .encode_vec(1, CID)
         .encode_vec(1, CID);
     let mut bogus_data: Vec<u8> = header.into();
-    bogus_data.resize(1200, 66);
+    bogus_data.resize(MIN_INITIAL_PACKET_SIZE, 66);
 
     let bogus = datagram(bogus_data);
     assert!(server.process(Some(&bogus), now()).dgram().is_none());
@@ -425,8 +426,8 @@ fn bad_client_initial() {
         )
         .unwrap();
     assert_eq!(header_enc.len() + v.len(), ciphertext.len());
-    // Pad with zero to get up to 1200.
-    ciphertext.resize(1200, 0);
+    // Pad with zero to get up to MIN_INITIAL_PACKET_SIZE.
+    ciphertext.resize(MIN_INITIAL_PACKET_SIZE, 0);
 
     apply_header_protection(
         &hp,
@@ -488,7 +489,7 @@ fn bad_client_initial_connection_close() {
     let (aead, hp) = initial_aead_and_hp(d_cid, Role::Client);
     let (_, pn) = remove_header_protection(&hp, header, payload);
 
-    let mut payload_enc = Encoder::with_capacity(1200);
+    let mut payload_enc = Encoder::with_capacity(MIN_INITIAL_PACKET_SIZE);
     payload_enc.encode(&[0x1c, 0x01, 0x00, 0x00]); // Add a CONNECTION_CLOSE frame.
 
     // Make a new header with a 1 byte packet number length.
@@ -513,8 +514,8 @@ fn bad_client_initial_connection_close() {
         )
         .unwrap();
     assert_eq!(header_enc.len() + v.len(), ciphertext.len());
-    // Pad with zero to get up to 1200.
-    ciphertext.resize(1200, 0);
+    // Pad with zero to get up to MIN_INITIAL_PACKET_SIZE.
+    ciphertext.resize(MIN_INITIAL_PACKET_SIZE, 0);
 
     apply_header_protection(
         &hp,
diff --git a/test-fixture/src/assertions.rs b/test-fixture/src/assertions.rs
index 191c81f7ab..9e62e7167e 100644
--- a/test-fixture/src/assertions.rs
+++ b/test-fixture/src/assertions.rs
@@ -7,7 +7,7 @@
 use std::net::SocketAddr;
 
 use neqo_common::{Datagram, Decoder};
-use neqo_transport::{version::WireVersion, Version};
+use neqo_transport::{version::WireVersion, Version, MIN_INITIAL_PACKET_SIZE};
 
 use crate::{DEFAULT_ADDR, DEFAULT_ADDR_V4};
 
@@ -62,7 +62,7 @@ pub fn assert_vn(payload: &[u8]) {
 ///
 /// If the tests fail.
 pub fn assert_coalesced_0rtt(payload: &[u8]) {
-    assert!(payload.len() >= 1200);
+    assert!(payload.len() >= MIN_INITIAL_PACKET_SIZE);
     let mut dec = Decoder::from(payload);
     let initial_type = dec.decode_byte().unwrap(); // Initial
     let version = assert_default_version(&mut dec);