diff --git a/quinn/src/endpoint.rs b/quinn/src/endpoint.rs
index 761a2fc5f..442608cc5 100644
--- a/quinn/src/endpoint.rs
+++ b/quinn/src/endpoint.rs
@@ -11,7 +11,11 @@ use std::{
     task::{Context, Poll, RawWaker, RawWakerVTable, Waker},
 };
 
-#[cfg(all(not(wasm_browser), any(feature = "aws-lc-rs", feature = "ring")))]
+#[cfg(all(
+    not(wasm_browser),
+    any(feature = "runtime-tokio", feature = "runtime-smol"),
+    any(feature = "aws-lc-rs", feature = "ring"),
+))]
 use crate::runtime::default_runtime;
 use crate::{
     Instant,
@@ -25,7 +29,11 @@ use proto::{
     EndpointEvent, ServerConfig,
 };
 use rustc_hash::FxHashMap;
-#[cfg(all(not(wasm_browser), any(feature = "aws-lc-rs", feature = "ring"),))]
+#[cfg(all(
+    not(wasm_browser),
+    any(feature = "runtime-tokio", feature = "runtime-smol"),
+    any(feature = "aws-lc-rs", feature = "ring"),
+))]
 use socket2::{Domain, Protocol, Socket, Type};
 use tokio::sync::{Notify, futures::Notified, mpsc};
 use tracing::{Instrument, Span};
@@ -67,7 +75,11 @@ impl Endpoint {
     ///
     /// Some environments may not allow creation of dual-stack sockets, in which case an IPv6
     /// client will only be able to connect to IPv6 servers. An IPv4 client is never dual-stack.
-    #[cfg(all(not(wasm_browser), any(feature = "aws-lc-rs", feature = "ring")))] // `EndpointConfig::default()` is only available with these
+    #[cfg(all(
+        not(wasm_browser),
+        any(feature = "runtime-tokio", feature = "runtime-smol"),
+        any(feature = "aws-lc-rs", feature = "ring"), // `EndpointConfig::default()` is only available with these
+    ))]
     pub fn client(addr: SocketAddr) -> io::Result<Self> {
         let socket = Socket::new(Domain::for_address(addr), Type::DGRAM, Some(Protocol::UDP))?;
         if addr.is_ipv6() {
@@ -97,7 +109,11 @@ impl Endpoint {
     /// IPv6 address on Windows will not by default be able to communicate with IPv4
     /// addresses. Portable applications should bind an address that matches the family they wish to
     /// communicate within.
-    #[cfg(all(not(wasm_browser), any(feature = "aws-lc-rs", feature = "ring")))] // `EndpointConfig::default()` is only available with these
+    #[cfg(all(
+        not(wasm_browser),
+        any(feature = "runtime-tokio", feature = "runtime-smol"),
+        any(feature = "aws-lc-rs", feature = "ring"), // `EndpointConfig::default()` is only available with these
+    ))]
     pub fn server(config: ServerConfig, addr: SocketAddr) -> io::Result<Self> {
         let socket = std::net::UdpSocket::bind(addr)?;
         let runtime =
diff --git a/quinn/src/lib.rs b/quinn/src/lib.rs
index 64f4800bb..61b7eb64a 100644
--- a/quinn/src/lib.rs
+++ b/quinn/src/lib.rs
@@ -85,7 +85,9 @@ pub use crate::recv_stream::{ReadError, ReadExactError, ReadToEndError, RecvStre
 pub use crate::runtime::SmolRuntime;
 #[cfg(feature = "runtime-tokio")]
 pub use crate::runtime::TokioRuntime;
-pub use crate::runtime::{AsyncTimer, AsyncUdpSocket, Runtime, UdpSender, default_runtime};
+#[cfg(any(feature = "runtime-tokio", feature = "runtime-smol"))]
+pub use crate::runtime::default_runtime;
+pub use crate::runtime::{AsyncTimer, AsyncUdpSocket, Runtime, UdpSender};
 pub use crate::send_stream::{SendStream, StoppedError, WriteError};
 
 #[cfg(test)]
diff --git a/quinn/src/runtime/mod.rs b/quinn/src/runtime/mod.rs
index 907b1992b..15a7a1112 100644
--- a/quinn/src/runtime/mod.rs
+++ b/quinn/src/runtime/mod.rs
@@ -1,10 +1,11 @@
+#[cfg(any(feature = "runtime-tokio", feature = "runtime-smol"))]
+use std::sync::Arc;
 use std::{
     fmt::{self, Debug},
     future::Future,
     io::{self, IoSliceMut},
     net::SocketAddr,
     pin::Pin,
-    sync::Arc,
     task::{Context, Poll},
 };
 
@@ -219,6 +220,7 @@ trait UdpSenderHelperSocket: Send + Sync + 'static {
 /// If `runtime-tokio` is enabled and this function is called from within a Tokio runtime context,
 /// then `TokioRuntime` is returned. Otherwise, if `runtime-smol` is enabled, `SmolRuntime` is
 /// returned. Otherwise, `None` is returned.
+#[cfg(any(feature = "runtime-tokio", feature = "runtime-smol"))]
 #[allow(clippy::needless_return)] // Be sure we return the right thing
 pub fn default_runtime() -> Option<Arc<dyn Runtime>> {
     #[cfg(feature = "runtime-tokio")]