diff --git a/openpgp-card-sequoia/src/lib.rs b/openpgp-card-sequoia/src/lib.rs
index f2284b5..6928b23 100644
--- a/openpgp-card-sequoia/src/lib.rs
+++ b/openpgp-card-sequoia/src/lib.rs
@@ -779,7 +779,8 @@ impl Card<Admin<'_, '_>> {
         // Check for max len
         let ec = self.state.tx.extended_capabilities()?;
 
-        if ec.max_len_special_do() == None || url.len() <= ec.max_len_special_do().unwrap() as usize
+        if ec.max_len_special_do().is_none()
+            || url.len() <= ec.max_len_special_do().unwrap() as usize
         {
             // If we don't know the max length for URL ("special DO"),
             // or if it's within the acceptable length:
diff --git a/openpgp-card/src/algorithm.rs b/openpgp-card/src/algorithm.rs
index c063b47..0e81124 100644
--- a/openpgp-card/src/algorithm.rs
+++ b/openpgp-card/src/algorithm.rs
@@ -201,7 +201,7 @@ impl Algo {
         let mut algo_attributes = vec![0x01];
 
         // Length of modulus n in bit
-        algo_attributes.extend(&algo_attrs.len_n().to_be_bytes());
+        algo_attributes.extend(algo_attrs.len_n().to_be_bytes());
 
         // Length of public exponent e in bit
         algo_attributes.push(0x00);
diff --git a/pcsc/src/lib.rs b/pcsc/src/lib.rs
index c7b93f1..1258c45 100644
--- a/pcsc/src/lib.rs
+++ b/pcsc/src/lib.rs
@@ -302,7 +302,7 @@ impl CardTransaction for PcscTransaction<'_> {
         ];
 
         // 15 ulDataLength ULONG length of Data to be sent to the ICC
-        send.extend(&(ab_data.len() as u32).to_le_bytes());
+        send.extend((ab_data.len() as u32).to_le_bytes());
 
         // 19 abData BYTE[] Data to send to the ICC
         send.extend(ab_data);
@@ -405,7 +405,7 @@ impl CardTransaction for PcscTransaction<'_> {
         ];
 
         // 15 ulDataLength ULONG length of Data to be sent to the ICC
-        send.extend(&(ab_data.len() as u32).to_le_bytes());
+        send.extend((ab_data.len() as u32).to_le_bytes());
 
         // 19 abData BYTE[] Data to send to the ICC
         send.extend(ab_data);
diff --git a/tools/src/util.rs b/tools/src/util.rs
index 6e3e08d..af846e1 100644
--- a/tools/src/util.rs
+++ b/tools/src/util.rs
@@ -230,7 +230,8 @@ pub(crate) fn print_gnuk_note(err: Error, card: &Card<Transaction>) -> Result<()
     ) {
         // check if no keys exist on the card
         let fps = card.fingerprints()?;
-        if fps.signature() == None && fps.decryption() == None && fps.authentication() == None {
+        if fps.signature().is_none() && fps.decryption().is_none() && fps.authentication().is_none()
+        {
             println!(
                 "\nNOTE: Some cards (e.g. Gnuk) don't allow \
                         User PIN change while no keys exist on the card."