diff --git a/build_tools b/build_tools
index b5ff34023..27df20c41 160000
--- a/build_tools
+++ b/build_tools
@@ -1 +1 @@
-Subproject commit b5ff34023b95625a9a7c9729bbf8ff1f0e9aab38
+Subproject commit 27df20c41e9525db6f67e57cb4161bdc8e82c117
diff --git a/xb.bat b/xb.bat
index 7b9120048..5b8005819 100644
--- a/xb.bat
+++ b/xb.bat
@@ -40,6 +40,7 @@ IF %_RESULT% NEQ 0 (
   ECHO this script again.
   GOTO :exit_error
 )
+CALL %VS14_VCVARSALL% amd64
 
 SET CLANG_FORMAT=""
 SET LLVM_CLANG_FORMAT="C:\Program Files (x86)\LLVM\bin\clang-format.exe"