diff --git a/quinn-proto/src/connection/streams/state.rs b/quinn-proto/src/connection/streams/state.rs
index 07f6d199e..a701d31bd 100644
--- a/quinn-proto/src/connection/streams/state.rs
+++ b/quinn-proto/src/connection/streams/state.rs
@@ -1168,7 +1168,7 @@ mod tests {
             initial_max_streams_uni: 1u32.into(),
             initial_max_data: 42u32.into(),
             initial_max_stream_data_uni: 42u32.into(),
-            ..Default::default()
+            ..TransportParameters::default()
         });
 
         let (mut pending, state) = (Retransmits::default(), ConnState::Established);
@@ -1227,7 +1227,7 @@ mod tests {
             initial_max_streams_bidi: 3u32.into(),
             initial_max_data: 10u32.into(),
             initial_max_stream_data_bidi_remote: 10u32.into(),
-            ..Default::default()
+            ..TransportParameters::default()
         });
 
         let (mut pending, state) = (Retransmits::default(), ConnState::Established);
@@ -1283,7 +1283,7 @@ mod tests {
             initial_max_streams_bidi: 3u32.into(),
             initial_max_data: 1000u32.into(),
             initial_max_stream_data_bidi_remote: 1000u32.into(),
-            ..Default::default()
+            ..TransportParameters::default()
         });
 
         let (mut pending, state) = (Retransmits::default(), ConnState::Established);
@@ -1377,7 +1377,7 @@ mod tests {
             initial_max_streams_uni: 1u32.into(),
             initial_max_data: 42u32.into(),
             initial_max_stream_data_uni: 42u32.into(),
-            ..Default::default()
+            ..TransportParameters::default()
         });
         let (mut pending, state) = (Retransmits::default(), ConnState::Established);
         let mut streams = Streams {
diff --git a/quinn-proto/src/transport_parameters.rs b/quinn-proto/src/transport_parameters.rs
index 9335858a8..78a3e18c7 100644
--- a/quinn-proto/src/transport_parameters.rs
+++ b/quinn-proto/src/transport_parameters.rs
@@ -101,9 +101,12 @@ macro_rules! make_struct {
             pub(crate) preferred_address: Option<PreferredAddress>,
         }
 
-        impl Default for TransportParameters {
+        // We deliberately don't implement the `Default` trait, since that would be public, and
+        // downstream crates should never construct `TransportParameters` except by decoding those
+        // supplied by a peer.
+        impl TransportParameters {
             /// Standard defaults, used if the peer does not supply a given parameter.
-            fn default() -> Self {
+            pub(crate) fn default() -> Self {
                 Self {
                     $($name: VarInt::from_u32($default),)*
 
@@ -528,11 +531,11 @@ mod test {
     fn resumption_params_validation() {
         let high_limit = TransportParameters {
             initial_max_streams_uni: 32u32.into(),
-            ..Default::default()
+            ..TransportParameters::default()
         };
         let low_limit = TransportParameters {
             initial_max_streams_uni: 16u32.into(),
-            ..Default::default()
+            ..TransportParameters::default()
         };
         high_limit.validate_resumption_from(&low_limit).unwrap();
         low_limit.validate_resumption_from(&high_limit).unwrap_err();