diff --git a/Cargo.toml b/Cargo.toml
index 841c4b9..b20d732 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -11,6 +11,7 @@ authors = ["Sean McArthur <sean@seanmonstar.com>"]
 keywords = ["http", "hyper", "hyperium"]
 categories = ["network-programming", "web-programming::http-client", "web-programming::http-server"]
 edition = "2018"
+resolver = "2"
 
 [package.metadata.docs.rs]
 features = ["full"]
diff --git a/src/common/mod.rs b/src/common/mod.rs
index 160df72..496a887 100644
--- a/src/common/mod.rs
+++ b/src/common/mod.rs
@@ -1,5 +1,6 @@
 #![allow(missing_docs)]
 
+#[allow(unused)]
 macro_rules! ready {
     ($e:expr) => {
         match $e {
@@ -9,6 +10,7 @@ macro_rules! ready {
     };
 }
 
+#[allow(unused)]
 pub(crate) use ready;
 pub(crate) mod exec;
 #[cfg(feature = "client")]
diff --git a/src/server/conn/auto.rs b/src/server/conn/auto.rs
index 2747191..0de9d3e 100644
--- a/src/server/conn/auto.rs
+++ b/src/server/conn/auto.rs
@@ -13,23 +13,35 @@ use http::{Request, Response};
 use http_body::Body;
 use hyper::{
     body::Incoming,
-    rt::{bounds::Http2ServerConnExec, Read, ReadBuf, Timer, Write},
-    server::conn::{http1, http2},
+    rt::{Read, ReadBuf, Timer, Write},
     service::Service,
 };
+
+#[cfg(feature = "http1")]
+use hyper::server::conn::http1;
+
+#[cfg(feature = "http2")]
+use hyper::{rt::bounds::Http2ServerConnExec, server::conn::http2};
+
 use pin_project_lite::pin_project;
 
 use crate::common::rewind::Rewind;
 
-type Result<T> = std::result::Result<T, Box<dyn std::error::Error + Send + Sync>>;
+type Error = Box<dyn std::error::Error + Send + Sync>;
+
+type Result<T> = std::result::Result<T, Error>;
 
 const H2_PREFACE: &[u8] = b"PRI * HTTP/2.0\r\n\r\nSM\r\n\r\n";
 
 /// Http1 or Http2 connection builder.
 #[derive(Clone, Debug)]
 pub struct Builder<E> {
+    #[cfg(feature = "http1")]
     http1: http1::Builder,
+    #[cfg(feature = "http2")]
     http2: http2::Builder<E>,
+    #[cfg(not(feature = "http2"))]
+    _executor: E,
 }
 
 impl<E> Builder<E> {
@@ -50,22 +62,29 @@ impl<E> Builder<E> {
     /// ```
     pub fn new(executor: E) -> Self {
         Self {
+            #[cfg(feature = "http1")]
             http1: http1::Builder::new(),
+            #[cfg(feature = "http2")]
             http2: http2::Builder::new(executor),
+            #[cfg(not(feature = "http2"))]
+            _executor: executor,
         }
     }
 
     /// Http1 configuration.
+    #[cfg(feature = "http1")]
     pub fn http1(&mut self) -> Http1Builder<'_, E> {
         Http1Builder { inner: self }
     }
 
     /// Http2 configuration.
+    #[cfg(feature = "http2")]
     pub fn http2(&mut self) -> Http2Builder<'_, E> {
         Http2Builder { inner: self }
     }
 
     /// Bind a connection together with a [`Service`].
+    #[cfg(feature = "http2")]
     pub async fn serve_connection<I, S, B>(&self, io: I, service: S) -> Result<()>
     where
         S: Service<Request<Incoming>, Response = Response<B>>,
@@ -78,8 +97,32 @@ impl<E> Builder<E> {
     {
         let (version, io) = read_version(io).await?;
         match version {
+            #[cfg(feature = "http1")]
             Version::H1 => self.http1.serve_connection(io, service).await?,
             Version::H2 => self.http2.serve_connection(io, service).await?,
+            #[cfg(any(not(feature = "http2"), not(feature = "http1")))]
+            version => return Err(version.unsupported()),
+        }
+
+        Ok(())
+    }
+
+    /// Bind a connection together with a [`Service`].
+    #[cfg(not(feature = "http2"))]
+    pub async fn serve_connection<I, S, B>(&self, io: I, service: S) -> Result<()>
+    where
+        S: Service<Request<Incoming>, Response = Response<B>>,
+        S::Future: 'static,
+        S::Error: Into<Box<dyn StdError + Send + Sync>>,
+        B: Body + 'static,
+        B::Error: Into<Box<dyn StdError + Send + Sync>>,
+        I: Read + Write + Unpin + 'static,
+    {
+        let (version, io) = read_version(io).await?;
+        match version {
+            #[cfg(feature = "http1")]
+            Version::H1 => self.http1.serve_connection(io, service).await?,
+            version => return Err(version.unsupported()),
         }
 
         Ok(())
@@ -88,6 +131,7 @@ impl<E> Builder<E> {
     /// Bind a connection together with a [`Service`], with the ability to
     /// handle HTTP upgrades. This requires that the IO object implements
     /// `Send`.
+    #[cfg(feature = "http2")]
     pub async fn serve_connection_with_upgrades<I, S, B>(&self, io: I, service: S) -> Result<()>
     where
         S: Service<Request<Incoming>, Response = Response<B>>,
@@ -100,6 +144,7 @@ impl<E> Builder<E> {
     {
         let (version, io) = read_version(io).await?;
         match version {
+            #[cfg(feature = "http1")]
             Version::H1 => {
                 self.http1
                     .serve_connection(io, service)
@@ -107,6 +152,37 @@ impl<E> Builder<E> {
                     .await?
             }
             Version::H2 => self.http2.serve_connection(io, service).await?,
+            #[cfg(any(not(feature = "http2"), not(feature = "http1")))]
+            version => return Err(version.unsupported()),
+        }
+
+        Ok(())
+    }
+
+    /// Bind a connection together with a [`Service`], with the ability to
+    /// handle HTTP upgrades. This requires that the IO object implements
+    /// `Send`.
+    #[cfg(not(feature = "http2"))]
+    pub async fn serve_connection_with_upgrades<I, S, B>(&self, io: I, service: S) -> Result<()>
+    where
+        S: Service<Request<Incoming>, Response = Response<B>>,
+        S::Future: 'static,
+        S::Error: Into<Box<dyn StdError + Send + Sync>>,
+        B: Body + 'static,
+        B::Error: Into<Box<dyn StdError + Send + Sync>>,
+        I: Read + Write + Unpin + Send + 'static,
+    {
+        let (version, io) = read_version(io).await?;
+        match version {
+            #[cfg(feature = "http1")]
+            Version::H1 => {
+                self.http1
+                    .serve_connection(io, service)
+                    .with_upgrades()
+                    .await?
+            }
+            #[cfg(any(not(feature = "http2"), not(feature = "http1")))]
+            version => return Err(version.unsupported()),
         }
 
         Ok(())
@@ -117,6 +193,18 @@ enum Version {
     H1,
     H2,
 }
+
+impl Version {
+    #[must_use]
+    #[cfg(any(not(feature = "http2"), not(feature = "http1")))]
+    pub fn unsupported(self) -> Error {
+        match self {
+            Version::H1 => Error::from("HTTP/1 is not supported"),
+            Version::H2 => Error::from("HTTP/2 is not supported"),
+        }
+    }
+}
+
 async fn read_version<'a, A>(mut reader: A) -> IoResult<(Version, Rewind<A>)>
 where
     A: Read + Unpin,
@@ -172,12 +260,15 @@ where
 }
 
 /// Http1 part of builder.
+#[cfg(feature = "http1")]
 pub struct Http1Builder<'a, E> {
     inner: &'a mut Builder<E>,
 }
 
+#[cfg(feature = "http1")]
 impl<E> Http1Builder<'_, E> {
     /// Http2 configuration.
+    #[cfg(feature = "http2")]
     pub fn http2(&mut self) -> Http2Builder<'_, E> {
         Http2Builder {
             inner: &mut self.inner,
@@ -292,6 +383,7 @@ impl<E> Http1Builder<'_, E> {
     }
 
     /// Bind a connection together with a [`Service`].
+    #[cfg(feature = "http2")]
     pub async fn serve_connection<I, S, B>(&self, io: I, service: S) -> Result<()>
     where
         S: Service<Request<Incoming>, Response = Response<B>>,
@@ -304,14 +396,31 @@ impl<E> Http1Builder<'_, E> {
     {
         self.inner.serve_connection(io, service).await
     }
+
+    /// Bind a connection together with a [`Service`].
+    #[cfg(not(feature = "http2"))]
+    pub async fn serve_connection<I, S, B>(&self, io: I, service: S) -> Result<()>
+    where
+        S: Service<Request<Incoming>, Response = Response<B>>,
+        S::Future: 'static,
+        S::Error: Into<Box<dyn StdError + Send + Sync>>,
+        B: Body + 'static,
+        B::Error: Into<Box<dyn StdError + Send + Sync>>,
+        I: Read + Write + Unpin + 'static,
+    {
+        self.inner.serve_connection(io, service).await
+    }
 }
 
 /// Http2 part of builder.
+#[cfg(feature = "http2")]
 pub struct Http2Builder<'a, E> {
     inner: &'a mut Builder<E>,
 }
 
+#[cfg(feature = "http2")]
 impl<E> Http2Builder<'_, E> {
+    #[cfg(feature = "http1")]
     /// Http1 configuration.
     pub fn http1(&mut self) -> Http1Builder<'_, E> {
         Http1Builder {
diff --git a/src/server/conn/mod.rs b/src/server/conn/mod.rs
index 535aee2..b23503a 100644
--- a/src/server/conn/mod.rs
+++ b/src/server/conn/mod.rs
@@ -1,4 +1,4 @@
 //! Connection utilities.
 
-#[cfg(feature = "server-auto")]
+#[cfg(any(feature = "http1", feature = "http2"))]
 pub mod auto;