diff --git a/src/lib.rs b/src/lib.rs
index 8215418c..790b6182 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -35,6 +35,7 @@
 #![deny(dead_code)]
 #![deny(unused_imports)]
 #![deny(missing_docs)]
+#![deny(unused_must_use)]
 
 // Re-exported dependencies.
 #[macro_use] pub extern crate bitcoin_hashes as hashes;
diff --git a/src/util/address.rs b/src/util/address.rs
index 182aee5a..2c26e7cf 100644
--- a/src/util/address.rs
+++ b/src/util/address.rs
@@ -222,7 +222,7 @@ impl Address {
     #[inline]
     pub fn p2pkh(pk: &key::PublicKey, network: Network) -> Address {
         let mut hash_engine = PubkeyHash::engine();
-        pk.write_into(&mut hash_engine);
+        pk.write_into(&mut hash_engine).expect("engines don't error");
 
         Address {
             network: network,
@@ -250,7 +250,7 @@ impl Address {
         }
 
         let mut hash_engine = WPubkeyHash::engine();
-        pk.write_into(&mut hash_engine);
+        pk.write_into(&mut hash_engine).expect("engines don't error");
 
         Ok(Address {
             network: network,
@@ -271,7 +271,7 @@ impl Address {
         }
 
         let mut hash_engine = WPubkeyHash::engine();
-        pk.write_into(&mut hash_engine);
+        pk.write_into(&mut hash_engine).expect("engines don't error");
 
         let builder = script::Builder::new()
             .push_int(0)
diff --git a/src/util/bip32.rs b/src/util/bip32.rs
index 0e27d95d..ad179be8 100644
--- a/src/util/bip32.rs
+++ b/src/util/bip32.rs
@@ -575,7 +575,7 @@ impl ExtendedPubKey {
     /// Returns the HASH160 of the public key of the xpub
     pub fn identifier(&self) -> XpubIdentifier {
         let mut engine = XpubIdentifier::engine();
-        self.public_key.write_into(&mut engine);
+        self.public_key.write_into(&mut engine).expect("engines don't error");
         XpubIdentifier::from_engine(engine)
     }
 
diff --git a/src/util/key.rs b/src/util/key.rs
index bf68cfd5..52cc97c8 100644
--- a/src/util/key.rs
+++ b/src/util/key.rs
@@ -101,18 +101,18 @@ impl PublicKey {
     }
 
     /// Write the public key into a writer
-    pub fn write_into<W: io::Write>(&self, mut writer: W) {
-        let _: io::Result<()> = if self.compressed {
+    pub fn write_into<W: io::Write>(&self, mut writer: W) -> Result<(), io::Error> {
+        if self.compressed {
             writer.write_all(&self.key.serialize())
         } else {
             writer.write_all(&self.key.serialize_uncompressed())
-        };
+        }
     }
 
     /// Serialize the public key to bytes
     pub fn to_bytes(&self) -> Vec<u8> {
         let mut buf = Vec::new();
-        self.write_into(&mut buf);
+        self.write_into(&mut buf).expect("vecs don't error");
         buf
     }
 
diff --git a/src/util/psbt/serialize.rs b/src/util/psbt/serialize.rs
index c64b2655..7344c73f 100644
--- a/src/util/psbt/serialize.rs
+++ b/src/util/psbt/serialize.rs
@@ -63,7 +63,7 @@ impl Deserialize for Script {
 impl Serialize for PublicKey {
     fn serialize(&self) -> Vec<u8> {
         let mut buf = Vec::new();
-        self.write_into(&mut buf);
+        self.write_into(&mut buf).expect("vecs don't error");
         buf
     }
 }