diff --git a/HISTORY.md b/HISTORY.md
index a27971795..e2ec3265c 100644
--- a/HISTORY.md
+++ b/HISTORY.md
@@ -17,6 +17,7 @@
 * Adjust WriteBufferManager's dummy entry size to block cache from 1MB to 256KB.
 * Fix a race condition between WritePrepared::Get and ::Put with duplicate keys.
 * Fix crash when memtable prefix bloom is enabled and read/write a key out of domain of prefix extractor.
+* Close a WAL file before another thread deletes it.
 
 ## 6.1.1 (4/9/2019)
 ### New Features
diff --git a/db/db_impl.cc b/db/db_impl.cc
index 27ffac50f..c6268d0cb 100644
--- a/db/db_impl.cc
+++ b/db/db_impl.cc
@@ -1209,7 +1209,15 @@ void DBImpl::BackgroundCallPurge() {
   // both queues are empty. This is stricter than what is needed, but can make
   // it easier for us to reason the correctness.
   while (!purge_queue_.empty() || !logs_to_free_queue_.empty()) {
-    if (!purge_queue_.empty()) {
+    // Check logs_to_free_queue_ first and close log writers.
+    if (!logs_to_free_queue_.empty()) {
+      assert(!logs_to_free_queue_.empty());
+      log::Writer* log_writer = *(logs_to_free_queue_.begin());
+      logs_to_free_queue_.pop_front();
+      mutex_.Unlock();
+      delete log_writer;
+      mutex_.Lock();
+    } else {
       auto purge_file = purge_queue_.begin();
       auto fname = purge_file->fname;
       auto dir_to_sync = purge_file->dir_to_sync;
@@ -1221,13 +1229,6 @@ void DBImpl::BackgroundCallPurge() {
       mutex_.Unlock();
       DeleteObsoleteFileImpl(job_id, fname, dir_to_sync, type, number);
       mutex_.Lock();
-    } else {
-      assert(!logs_to_free_queue_.empty());
-      log::Writer* log_writer = *(logs_to_free_queue_.begin());
-      logs_to_free_queue_.pop_front();
-      mutex_.Unlock();
-      delete log_writer;
-      mutex_.Lock();
     }
   }
   bg_purge_scheduled_--;
diff --git a/db/db_impl_files.cc b/db/db_impl_files.cc
index 90cc6a14b..b16cf8794 100644
--- a/db/db_impl_files.cc
+++ b/db/db_impl_files.cc
@@ -481,6 +481,11 @@ void DBImpl::PurgeObsoleteFiles(JobContext& state, bool schedule_only) {
     }
 #endif  // !ROCKSDB_LITE
 
+    for (const auto w : state.logs_to_free) {
+      // TODO: maybe check the return value of Close.
+      w->Close();
+    }
+
     Status file_deletion_status;
     if (schedule_only) {
       InstrumentedMutexLock guard_lock(&mutex_);
diff --git a/db/log_writer.cc b/db/log_writer.cc
index bc99931b9..6ee391981 100644
--- a/db/log_writer.cc
+++ b/db/log_writer.cc
@@ -31,10 +31,23 @@ Writer::Writer(std::unique_ptr<WritableFileWriter>&& dest, uint64_t log_number,
   }
 }
 
-Writer::~Writer() { WriteBuffer(); }
+Writer::~Writer() {
+  if (dest_) {
+    WriteBuffer();
+  }
+}
 
 Status Writer::WriteBuffer() { return dest_->Flush(); }
 
+Status Writer::Close() {
+  Status s;
+  if (dest_) {
+    s = dest_->Close();
+    dest_.reset();
+  }
+  return s;
+}
+
 Status Writer::AddRecord(const Slice& slice) {
   const char* ptr = slice.data();
   size_t left = slice.size();
diff --git a/db/log_writer.h b/db/log_writer.h
index 3638beb7e..116d03358 100644
--- a/db/log_writer.h
+++ b/db/log_writer.h
@@ -84,6 +84,8 @@ class Writer {
 
   Status WriteBuffer();
 
+  Status Close();
+
   bool TEST_BufferIsEmpty();
 
  private: