Index: Setup/build.bat
==================================================================
--- Setup/build.bat
+++ Setup/build.bat
@@ -187,18 +187,22 @@
 REM       updating.
 REM
 IF NOT DEFINED MSBUILDDIR (
   CALL :fn_CheckMsBuildDir 14.0
   IF DEFINED MSBUILDDIR (
-    SET YEAR=2015
+    IF NOT DEFINED YEAR (
+      SET YEAR=2015
+    )
   )
 )
 
 IF NOT DEFINED MSBUILDDIR (
   CALL :fn_CheckMsBuildDir 12.0
   IF DEFINED MSBUILDDIR (
-    SET YEAR=2013
+    IF NOT DEFINED YEAR (
+      SET YEAR=2013
+    )
   )
 )
 
 REM
 REM TODO: When the next version of Visual Studio is released, this section
@@ -205,25 +209,31 @@
 REM       may need updating.
 REM
 IF NOT DEFINED FRAMEWORKDIR (
   CALL :fn_CheckFrameworkDir v4.0.30319
   IF DEFINED FRAMEWORKDIR (
-    SET YEAR=2010
+    IF NOT DEFINED YEAR (
+      SET YEAR=2010
+    )
   )
 )
 
 IF NOT DEFINED FRAMEWORKDIR (
   CALL :fn_CheckFrameworkDir v3.5
   IF DEFINED FRAMEWORKDIR (
-    SET YEAR=2008
+    IF NOT DEFINED YEAR (
+      SET YEAR=2008
+    )
   )
 )
 
 IF NOT DEFINED FRAMEWORKDIR (
   CALL :fn_CheckFrameworkDir v2.0.50727
   IF DEFINED FRAMEWORKDIR (
-    SET YEAR=2005
+    IF NOT DEFINED YEAR (
+      SET YEAR=2005
+    )
   )
 )
 
 :setup_buildToolDir