diff --git a/.changelog/unreleased/improvements/1413-reuse-sign-bytes.md b/.changelog/unreleased/improvements/1413-reuse-sign-bytes.md
new file mode 100644
index 000000000..4198ceae5
--- /dev/null
+++ b/.changelog/unreleased/improvements/1413-reuse-sign-bytes.md
@@ -0,0 +1,3 @@
+- `[tendermint-light-client-verifier]` Reuse buffer used to store
+  sign_bytes to reduce number of allocations and deallocations.
+  ([\#1413](https://github.com/informalsystems/tendermint-rs/pull/1413))
diff --git a/light-client-verifier/src/operations/voting_power.rs b/light-client-verifier/src/operations/voting_power.rs
index 1f7e9f0ed..0511cc426 100644
--- a/light-client-verifier/src/operations/voting_power.rs
+++ b/light-client-verifier/src/operations/voting_power.rs
@@ -264,6 +264,11 @@ impl NonAbsentCommitVote {
 struct NonAbsentCommitVotes {
     /// Votes sorted by validator address.
     votes: Vec<NonAbsentCommitVote>,
+    /// Internal buffer for storing sign_bytes.
+    ///
+    /// The buffer is reused for each canonical vote so that we allocate it
+    /// once.
+    sign_bytes: Vec<u8>,
 }
 
 impl NonAbsentCommitVotes {
@@ -297,7 +302,12 @@ impl NonAbsentCommitVotes {
                 pair[0].validator_id(),
             ))
         } else {
-            Ok(Self { votes })
+            // As of protocol 0.38, 160 buffer is enough for chain identifier up
+            // to 44 bytes.
+            Ok(Self {
+                votes,
+                sign_bytes: Vec::with_capacity(160),
+            })
         }
     }
 
@@ -319,14 +329,18 @@ impl NonAbsentCommitVotes {
         };
 
         if !vote.verified {
-            let sign_bytes = vote.signed_vote.sign_bytes();
+            self.sign_bytes.truncate(0);
+            vote.signed_vote
+                .sign_bytes_into(&mut self.sign_bytes)
+                .unwrap();
+            let sign_bytes = self.sign_bytes.as_slice();
             validator
-                .verify_signature::<V>(&sign_bytes, vote.signed_vote.signature())
+                .verify_signature::<V>(sign_bytes, vote.signed_vote.signature())
                 .map_err(|_| {
                     VerificationError::invalid_signature(
                         vote.signed_vote.signature().as_bytes().to_vec(),
                         Box::new(validator.clone()),
-                        sign_bytes,
+                        sign_bytes.to_vec(),
                     )
                 })?;
         }
diff --git a/tendermint/src/vote.rs b/tendermint/src/vote.rs
index cd37c728d..a4cd82ce0 100644
--- a/tendermint/src/vote.rs
+++ b/tendermint/src/vote.rs
@@ -329,6 +329,10 @@ impl SignedVote {
         Protobuf::<RawCanonicalVote>::encode_length_delimited_vec(self.vote.clone())
     }
 
+    pub fn sign_bytes_into(&self, buf: &mut impl BufMut) -> Result<(), ProtobufError> {
+        Protobuf::<RawCanonicalVote>::encode_length_delimited(self.vote.clone(), buf)
+    }
+
     /// Return the actual signature on the canonicalized vote.
     pub fn signature(&self) -> &Signature {
         &self.signature