diff --git a/cpp/array_record_writer.cc b/cpp/array_record_writer.cc
index ef722af..1edd276 100644
--- a/cpp/array_record_writer.cc
+++ b/cpp/array_record_writer.cc
@@ -250,7 +250,7 @@ class ArrayRecordWriterBase::SubmitChunkCallback
   // return false if we can't schedule the callback.
   // return true and inc num_concurrent_chunk_writers if we can add a new one.
   bool TrackConcurrentChunkWriters() {
-    absl::MutexLock l(&mu_);
+    absl::MutexLock l(mu_);
     if (num_concurrent_chunk_writers_ >= max_parallelism_) {
       return false;
     }
@@ -495,7 +495,7 @@ void ArrayRecordWriterBase::SubmitChunkCallback::operator()(
   footer.set_num_records(num_records);
   array_footer_.push_back(std::move(footer));
 
-  absl::MutexLock l(&mu_);
+  absl::MutexLock l(mu_);
   num_concurrent_chunk_writers_--;
 }
 
diff --git a/cpp/sequenced_chunk_writer.cc b/cpp/sequenced_chunk_writer.cc
index 23b15f1..6a25bc4 100644
--- a/cpp/sequenced_chunk_writer.cc
+++ b/cpp/sequenced_chunk_writer.cc
@@ -34,7 +34,7 @@ namespace array_record {
 
 bool SequencedChunkWriterBase::CommitFutureChunk(
     std::future<absl::StatusOr<riegeli::Chunk>>&& future_chunk) {
-  absl::MutexLock l(&mu_);
+  absl::MutexLock l(mu_);
   if (!ok()) {
     return false;
   }
@@ -64,13 +64,13 @@ bool SequencedChunkWriterBase::SubmitFutureChunks(bool block) {
   if (block) {
     // When blocking, we block both on mutex acquisition and on future
     // completion.
-    absl::MutexLock lock(&mu_);
+    absl::MutexLock lock(mu_);
     riegeli::ChunkWriter* writer = get_writer();
     while (!queue_.empty()) {
       TrySubmitFirstFutureChunk(writer);
     }
     return ok();
-  } else if (mu_.TryLock()) {
+  } else if (mu_.try_lock()) {
     // When non-blocking, we only proceed if we can lock the mutex without
     // blocking, and we only process those futures that are ready. We need
     // to unlock the mutex manually in this case, and take care to call ok()
@@ -82,7 +82,7 @@ bool SequencedChunkWriterBase::SubmitFutureChunks(bool block) {
       TrySubmitFirstFutureChunk(writer);
     }
     bool result = ok();
-    mu_.Unlock();
+    mu_.unlock();
     return result;
   } else {
     return true;