diff --git a/db/db_impl.cc b/db/db_impl.cc
index fb173b42d..918402df5 100644
--- a/db/db_impl.cc
+++ b/db/db_impl.cc
@@ -892,6 +892,16 @@ void DBImpl::PurgeObsoleteWALFiles() {
   }
 }
 
+namespace {
+struct CompareLogByPointer {
+  bool operator()(const unique_ptr<LogFile>& a, const unique_ptr<LogFile>& b) {
+    LogFileImpl* a_impl = dynamic_cast<LogFileImpl*>(a.get());
+    LogFileImpl* b_impl = dynamic_cast<LogFileImpl*>(b.get());
+    return *a_impl < *b_impl;
+  }
+};
+}
+
 Status DBImpl::GetSortedWalsOfType(const std::string& path,
                                    VectorLogPtr& log_files,
                                    WalFileType log_type) {
@@ -1045,14 +1055,6 @@ Status DBImpl::ReadFirstLine(const std::string& fname,
   return status;
 }
 
-struct CompareLogByPointer {
-  bool operator()(const unique_ptr<LogFile>& a, const unique_ptr<LogFile>& b) {
-    LogFileImpl* a_impl = dynamic_cast<LogFileImpl*>(a.get());
-    LogFileImpl* b_impl = dynamic_cast<LogFileImpl*>(b.get());
-    return *a_impl < *b_impl;
-  }
-};
-
 #endif  // ROCKSDB_LITE
 
 Status DBImpl::Recover(
diff --git a/db/db_impl_debug.cc b/db/db_impl_debug.cc
index 1d0b70d26..6736fe81b 100644
--- a/db/db_impl_debug.cc
+++ b/db/db_impl_debug.cc
@@ -11,6 +11,8 @@
 
 #include "db/db_impl.h"
 
+namespace rocksdb {
+
 void DBImpl::TEST_PurgeObsoleteteWAL() { PurgeObsoleteWALFiles(); }
 
 uint64_t DBImpl::TEST_GetLevel0TotalSize() {
@@ -116,4 +118,5 @@ Status DBImpl::TEST_WaitForCompact() {
   }
   return bg_error_;
 }
+}  // namespace rocksdb
 #endif  // NDEBUG