diff --git a/parsers/Cargo.toml b/parsers/Cargo.toml
index a72201ba..54393718 100644
--- a/parsers/Cargo.toml
+++ b/parsers/Cargo.toml
@@ -24,9 +24,6 @@ sha3 = "0.10"
 blake2 = "0.10.4"
 chrono = { version = "0.4.5", default-features = false, features = ["std"] }
 
-[build-dependencies]
-rustc_version = "0.4"
-
 [features]
 # Build xmpp-parsers to make components instead of clients.
 component = []
diff --git a/tokio-xmpp/Cargo.toml b/tokio-xmpp/Cargo.toml
index c2738149..b4ff77a1 100644
--- a/tokio-xmpp/Cargo.toml
+++ b/tokio-xmpp/Cargo.toml
@@ -34,9 +34,6 @@ syntect = { version = "5", optional = true }
 [dev-dependencies]
 env_logger = { version = "0.10", default-features = false, features = ["auto-color", "humantime"] }
 
-[build-dependencies]
-rustc_version = "0.4"
-
 [features]
 default = ["tls-native"]
 tls-rust = ["tokio-rustls", "webpki-roots"]
diff --git a/tokio-xmpp/build.rs b/tokio-xmpp/build.rs
deleted file mode 100644
index 6022bd5b..00000000
--- a/tokio-xmpp/build.rs
+++ /dev/null
@@ -1,11 +0,0 @@
-use rustc_version::version;
-
-fn main() {
-    let version = version().unwrap();
-
-    for major in 1..=version.major {
-        for minor in 0..=version.minor {
-            println!("cargo:rustc-cfg=rustc_least_{}_{}", major, minor);
-        }
-    }
-}
diff --git a/tokio-xmpp/src/xmpp_stream.rs b/tokio-xmpp/src/xmpp_stream.rs
index 1b13a0c4..c1f82bad 100644
--- a/tokio-xmpp/src/xmpp_stream.rs
+++ b/tokio-xmpp/src/xmpp_stream.rs
@@ -105,28 +105,19 @@ impl<S: AsyncRead + AsyncWrite + Unpin> Sink<Packet> for XMPPStream<S> {
         Poll::Ready(Ok(()))
     }
 
-    fn start_send(
-        #[cfg_attr(rustc_least_1_46, allow(unused_mut))] mut self: Pin<&mut Self>,
-        item: Packet,
-    ) -> Result<(), Self::Error> {
+    fn start_send(mut self: Pin<&mut Self>, item: Packet) -> Result<(), Self::Error> {
         Pin::new(&mut self.stream)
             .start_send(item)
             .map_err(|e| e.into())
     }
 
-    fn poll_flush(
-        #[cfg_attr(rustc_least_1_46, allow(unused_mut))] mut self: Pin<&mut Self>,
-        cx: &mut Context,
-    ) -> Poll<Result<(), Self::Error>> {
+    fn poll_flush(mut self: Pin<&mut Self>, cx: &mut Context) -> Poll<Result<(), Self::Error>> {
         Pin::new(&mut self.stream)
             .poll_flush(cx)
             .map_err(|e| e.into())
     }
 
-    fn poll_close(
-        #[cfg_attr(rustc_least_1_46, allow(unused_mut))] mut self: Pin<&mut Self>,
-        cx: &mut Context,
-    ) -> Poll<Result<(), Self::Error>> {
+    fn poll_close(mut self: Pin<&mut Self>, cx: &mut Context) -> Poll<Result<(), Self::Error>> {
         Pin::new(&mut self.stream)
             .poll_close(cx)
             .map_err(|e| e.into())
@@ -137,10 +128,7 @@ impl<S: AsyncRead + AsyncWrite + Unpin> Sink<Packet> for XMPPStream<S> {
 impl<S: AsyncRead + AsyncWrite + Unpin> Stream for XMPPStream<S> {
     type Item = Result<Packet, crate::Error>;
 
-    fn poll_next(
-        #[cfg_attr(rustc_least_1_46, allow(unused_mut))] mut self: Pin<&mut Self>,
-        cx: &mut Context,
-    ) -> Poll<Option<Self::Item>> {
+    fn poll_next(mut self: Pin<&mut Self>, cx: &mut Context) -> Poll<Option<Self::Item>> {
         Pin::new(&mut self.stream)
             .poll_next(cx)
             .map(|result| result.map(|result| result.map_err(|e| e.into())))