diff --git a/src/server/conn/auto.rs b/src/server/conn/auto.rs
index 47d88dc..703b2c4 100644
--- a/src/server/conn/auto.rs
+++ b/src/server/conn/auto.rs
@@ -58,6 +58,8 @@ pub struct Builder<E> {
     http1: http1::Builder,
     #[cfg(feature = "http2")]
     http2: http2::Builder<E>,
+    #[cfg(any(feature = "http1", feature = "http2"))]
+    version: Option<Version>,
     #[cfg(not(feature = "http2"))]
     _executor: E,
 }
@@ -84,6 +86,8 @@ impl<E> Builder<E> {
             http1: http1::Builder::new(),
             #[cfg(feature = "http2")]
             http2: http2::Builder::new(executor),
+            #[cfg(any(feature = "http1", feature = "http2"))]
+            version: None,
             #[cfg(not(feature = "http2"))]
             _executor: executor,
         }
@@ -101,6 +105,26 @@ impl<E> Builder<E> {
         Http2Builder { inner: self }
     }
 
+    /// Only accepts HTTP/2
+    ///
+    /// Does not do anything if used with [`serve_connection_with_upgrades`]
+    #[cfg(feature = "http2")]
+    pub fn http2_only(mut self) -> Self {
+        assert!(self.version.is_none());
+        self.version = Some(Version::H2);
+        self
+    }
+
+    /// Only accepts HTTP/1
+    ///
+    /// Does not do anything if used with [`serve_connection_with_upgrades`]
+    #[cfg(feature = "http1")]
+    pub fn http1_only(mut self) -> Self {
+        assert!(self.version.is_none());
+        self.version = Some(Version::H1);
+        self
+    }
+
     /// Bind a connection together with a [`Service`].
     pub fn serve_connection<I, S, B>(&self, io: I, service: S) -> Connection<'_, I, S, E>
     where
@@ -112,13 +136,28 @@ impl<E> Builder<E> {
         I: Read + Write + Unpin + 'static,
         E: HttpServerConnExec<S::Future, B>,
     {
-        Connection {
-            state: ConnState::ReadVersion {
+        let state = match self.version {
+            #[cfg(feature = "http1")]
+            Some(Version::H1) => {
+                let io = Rewind::new_buffered(io, Bytes::new());
+                let conn = self.http1.serve_connection(io, service);
+                ConnState::H1 { conn }
+            }
+            #[cfg(feature = "http2")]
+            Some(Version::H2) => {
+                let io = Rewind::new_buffered(io, Bytes::new());
+                let conn = self.http2.serve_connection(io, service);
+                ConnState::H2 { conn }
+            }
+            #[cfg(any(feature = "http1", feature = "http2"))]
+            _ => ConnState::ReadVersion {
                 read_version: read_version(io),
                 builder: self,
                 service: Some(service),
             },
-        }
+        };
+
+        Connection { state }
     }
 
     /// Bind a connection together with a [`Service`], with the ability to
@@ -148,7 +187,7 @@ impl<E> Builder<E> {
     }
 }
 
-#[derive(Copy, Clone)]
+#[derive(Copy, Clone, Debug)]
 enum Version {
     H1,
     H2,
@@ -906,7 +945,7 @@ mod tests {
     #[cfg(not(miri))]
     #[tokio::test]
     async fn http1() {
-        let addr = start_server().await;
+        let addr = start_server(false, false).await;
         let mut sender = connect_h1(addr).await;
 
         let response = sender
@@ -922,7 +961,23 @@ mod tests {
     #[cfg(not(miri))]
     #[tokio::test]
     async fn http2() {
-        let addr = start_server().await;
+        let addr = start_server(false, false).await;
+        let mut sender = connect_h2(addr).await;
+
+        let response = sender
+            .send_request(Request::new(Empty::<Bytes>::new()))
+            .await
+            .unwrap();
+
+        let body = response.into_body().collect().await.unwrap().to_bytes();
+
+        assert_eq!(body, BODY);
+    }
+
+    #[cfg(not(miri))]
+    #[tokio::test]
+    async fn http2_only() {
+        let addr = start_server(false, true).await;
         let mut sender = connect_h2(addr).await;
 
         let response = sender
@@ -935,6 +990,46 @@ mod tests {
         assert_eq!(body, BODY);
     }
 
+    #[cfg(not(miri))]
+    #[tokio::test]
+    async fn http2_only_fail_if_client_is_http1() {
+        let addr = start_server(false, true).await;
+        let mut sender = connect_h1(addr).await;
+
+        let _ = sender
+            .send_request(Request::new(Empty::<Bytes>::new()))
+            .await
+            .expect_err("should fail");
+    }
+
+    #[cfg(not(miri))]
+    #[tokio::test]
+    async fn http1_only() {
+        let addr = start_server(true, false).await;
+        let mut sender = connect_h1(addr).await;
+
+        let response = sender
+            .send_request(Request::new(Empty::<Bytes>::new()))
+            .await
+            .unwrap();
+
+        let body = response.into_body().collect().await.unwrap().to_bytes();
+
+        assert_eq!(body, BODY);
+    }
+
+    #[cfg(not(miri))]
+    #[tokio::test]
+    async fn http1_only_fail_if_client_is_http2() {
+        let addr = start_server(true, false).await;
+        let mut sender = connect_h2(addr).await;
+
+        let _ = sender
+            .send_request(Request::new(Empty::<Bytes>::new()))
+            .await
+            .expect_err("should fail");
+    }
+
     #[cfg(not(miri))]
     #[tokio::test]
     async fn graceful_shutdown() {
@@ -1000,7 +1095,7 @@ mod tests {
         sender
     }
 
-    async fn start_server() -> SocketAddr {
+    async fn start_server(h1_only: bool, h2_only: bool) -> SocketAddr {
         let addr: SocketAddr = ([127, 0, 0, 1], 0).into();
         let listener = TcpListener::bind(addr).await.unwrap();
 
@@ -1011,11 +1106,20 @@ mod tests {
                 let (stream, _) = listener.accept().await.unwrap();
                 let stream = TokioIo::new(stream);
                 tokio::task::spawn(async move {
-                    let _ = auto::Builder::new(TokioExecutor::new())
-                        .http2()
-                        .max_header_list_size(4096)
-                        .serve_connection_with_upgrades(stream, service_fn(hello))
-                        .await;
+                    let mut builder = auto::Builder::new(TokioExecutor::new());
+                    if h1_only {
+                        builder = builder.http1_only();
+                        builder.serve_connection(stream, service_fn(hello)).await;
+                    } else if h2_only {
+                        builder = builder.http2_only();
+                        builder.serve_connection(stream, service_fn(hello)).await;
+                    } else {
+                        builder
+                            .http2()
+                            .max_header_list_size(4096)
+                            .serve_connection_with_upgrades(stream, service_fn(hello))
+                            .await;
+                    }
                 });
             }
         });