diff --git a/hdfs/env_hdfs.h b/hdfs/env_hdfs.h
index 6303cb7af..a2543dfd3 100644
--- a/hdfs/env_hdfs.h
+++ b/hdfs/env_hdfs.h
@@ -89,7 +89,9 @@ class HdfsEnv : public Env {
 
   virtual Status RenameFile(const std::string& src, const std::string& target);
 
-  virtual Status LinkFile(const std::string& src, const std::string& target);
+  virtual Status LinkFile(const std::string& src, const std::string& target) {
+    return Status::NotSupported(); // not supported
+  }
 
   virtual Status LockFile(const std::string& fname, FileLock** lock);
 
diff --git a/util/env_hdfs.cc b/util/env_hdfs.cc
index 30e796245..e7844e8dc 100644
--- a/util/env_hdfs.cc
+++ b/util/env_hdfs.cc
@@ -18,6 +18,7 @@
 #include <iostream>
 #include <sstream>
 #include "rocksdb/status.h"
+#include "util/string_util.h"
 
 #define HDFS_EXISTS 0
 #define HDFS_DOESNT_EXIST -1