diff --git a/bitcoin/src/bip158.rs b/bitcoin/src/bip158.rs
index 61b3c6e2..49347977 100644
--- a/bitcoin/src/bip158.rs
+++ b/bitcoin/src/bip158.rs
@@ -271,9 +271,7 @@ impl GcsFilterReader {
         I::Item: Borrow<[u8]>,
         R: io::Read + ?Sized,
     {
-        let mut decoder = reader;
-        let n_elements: VarInt = Decodable::consensus_decode(&mut decoder).unwrap_or(VarInt(0));
-        let reader = &mut decoder;
+        let n_elements: VarInt = Decodable::consensus_decode(reader).unwrap_or(VarInt(0));
         // map hashes to [0, n_elements << grp]
         let nm = n_elements.0 * self.m;
         let mut mapped =
@@ -316,9 +314,7 @@ impl GcsFilterReader {
         I::Item: Borrow<[u8]>,
         R: io::Read + ?Sized,
     {
-        let mut decoder = reader;
-        let n_elements: VarInt = Decodable::consensus_decode(&mut decoder).unwrap_or(VarInt(0));
-        let reader = &mut decoder;
+        let n_elements: VarInt = Decodable::consensus_decode(reader).unwrap_or(VarInt(0));
         // map hashes to [0, n_elements << grp]
         let nm = n_elements.0 * self.m;
         let mut mapped =
@@ -442,7 +438,7 @@ impl GcsFilter {
     /// Golomb-Rice decodes a number from a bit stream (parameter 2^k).
     fn golomb_rice_decode<R>(&self, reader: &mut BitStreamReader<R>) -> Result<u64, io::Error>
     where
-        R: io::Read,
+        R: io::Read + ?Sized,
     {
         let mut q = 0u64;
         while reader.read(1)? == 1 {
@@ -459,13 +455,13 @@ impl GcsFilter {
 }
 
 /// Bitwise stream reader.
-pub struct BitStreamReader<'a, R> {
+pub struct BitStreamReader<'a, R: ?Sized> {
     buffer: [u8; 1],
     offset: u8,
     reader: &'a mut R,
 }
 
-impl<'a, R: io::Read> BitStreamReader<'a, R> {
+impl<'a, R: io::Read + ?Sized> BitStreamReader<'a, R> {
     /// Creates a new [`BitStreamReader`] that reads bitwise from a given `reader`.
     pub fn new(reader: &'a mut R) -> BitStreamReader<'a, R> {
         BitStreamReader { buffer: [0u8], reader, offset: 8 }
diff --git a/bitcoin/src/consensus/encode.rs b/bitcoin/src/consensus/encode.rs
index 42d11a1e..6d0a3a7b 100644
--- a/bitcoin/src/consensus/encode.rs
+++ b/bitcoin/src/consensus/encode.rs
@@ -662,8 +662,8 @@ struct ReadBytesFromFiniteReaderOpts {
 /// This function relies on reader being bound in amount of data
 /// it returns for OOM protection. See [`Decodable::consensus_decode_from_finite_reader`].
 #[inline]
-fn read_bytes_from_finite_reader<D: io::Read>(
-    mut d: D,
+fn read_bytes_from_finite_reader<D: io::Read + ?Sized>(
+    d: &mut D,
     mut opts: ReadBytesFromFiniteReaderOpts,
 ) -> Result<Vec<u8>, Error> {
     let mut ret = vec![];
@@ -1234,7 +1234,7 @@ mod tests {
         for chunk_size in 1..20 {
             assert_eq!(
                 read_bytes_from_finite_reader(
-                    io::Cursor::new(&data),
+                    &mut io::Cursor::new(&data),
                     ReadBytesFromFiniteReaderOpts { len: data.len(), chunk_size }
                 )
                 .unwrap(),
diff --git a/bitcoin/src/crypto/key.rs b/bitcoin/src/crypto/key.rs
index 7ba63a89..01ff2b13 100644
--- a/bitcoin/src/crypto/key.rs
+++ b/bitcoin/src/crypto/key.rs
@@ -76,7 +76,7 @@ impl PublicKey {
     ///
     /// This internally reads the first byte before reading the rest, so
     /// use of a `BufReader` is recommended.
-    pub fn read_from<R: io::Read>(mut reader: R) -> Result<Self, io::Error> {
+    pub fn read_from<R: io::Read + ?Sized>(reader: &mut R) -> Result<Self, io::Error> {
         let mut bytes = [0; 65];
 
         reader.read_exact(&mut bytes[0..1])?;
@@ -914,11 +914,11 @@ mod tests {
 
         // sanity checks
         assert!(PublicKey::read_from(&mut cursor).is_err());
-        assert!(PublicKey::read_from(io::Cursor::new(&[])).is_err());
-        assert!(PublicKey::read_from(io::Cursor::new(&[0; 33][..])).is_err());
-        assert!(PublicKey::read_from(io::Cursor::new(&[2; 32][..])).is_err());
-        assert!(PublicKey::read_from(io::Cursor::new(&[0; 65][..])).is_err());
-        assert!(PublicKey::read_from(io::Cursor::new(&[4; 64][..])).is_err());
+        assert!(PublicKey::read_from(&mut io::Cursor::new(&[])).is_err());
+        assert!(PublicKey::read_from(&mut io::Cursor::new(&[0; 33][..])).is_err());
+        assert!(PublicKey::read_from(&mut io::Cursor::new(&[2; 32][..])).is_err());
+        assert!(PublicKey::read_from(&mut io::Cursor::new(&[0; 65][..])).is_err());
+        assert!(PublicKey::read_from(&mut io::Cursor::new(&[4; 64][..])).is_err());
     }
 
     #[test]
diff --git a/bitcoin/src/psbt/raw.rs b/bitcoin/src/psbt/raw.rs
index effd805b..85275835 100644
--- a/bitcoin/src/psbt/raw.rs
+++ b/bitcoin/src/psbt/raw.rs
@@ -196,7 +196,7 @@ where
 }
 
 // core2 doesn't have read_to_end
-pub(crate) fn read_to_end<D: io::Read>(mut d: D) -> Result<Vec<u8>, io::Error> {
+pub(crate) fn read_to_end<D: io::Read + ?Sized>(d: &mut D) -> Result<Vec<u8>, io::Error> {
     let mut result = vec![];
     let mut buf = [0u8; 64];
     loop {