diff -ruN src\caffe2\db\lmdb.cc src-new\caffe2\db\lmdb.cc
--- src\caffe2\db\lmdb.cc	Tue May 09 18:15:14 2017
+++ src-new\caffe2\db\lmdb.cc	Tue May 09 17:52:09 2017
@@ -1,5 +1,9 @@
 #include "lmdb.h"  // NOLINT
 
+#if defined(_WIN32)
+#include <direct.h>
+#endif
+
 #include <sys/stat.h>
 
 #include <string>
@@ -138,8 +142,13 @@
   MDB_CHECK(mdb_env_create(&mdb_env_));
   MDB_CHECK(mdb_env_set_mapsize(mdb_env_, LMDB_MAP_SIZE));
   if (mode == NEW) {
+#if defined(_WIN32)
+    CAFFE_ENFORCE_EQ(
+        _mkdir(source.c_str()), 0, "mkdir ", source, " failed");
+#else
     CAFFE_ENFORCE_EQ(
         mkdir(source.c_str(), 0744), 0, "mkdir ", source, " failed");
+#endif
   }
   int flags = 0;
   if (mode == READ) {