Index: Setup/build_mono.bat
==================================================================
--- Setup/build_mono.bat
+++ Setup/build_mono.bat
@@ -53,10 +53,30 @@
   ECHO Could not detect Visual Studio.
   GOTO errors
 )
 
 CALL :fn_UnsetVariable YEARS
+
+IF NOT DEFINED NOVS2017 (
+  IF DEFINED VS2017SP (
+    SET YEARS=2017
+  ) ELSE (
+    ECHO Could not detect Visual Studio 2017.
+  )
+) ELSE (
+  ECHO Use of Visual Studio 2017 is disallowed.
+)
+
+IF NOT DEFINED NOVS2015 (
+  IF DEFINED VS2015SP (
+    SET YEARS=2015
+  ) ELSE (
+    ECHO Could not detect Visual Studio 2015.
+  )
+) ELSE (
+  ECHO Use of Visual Studio 2015 is disallowed.
+)
 
 IF NOT DEFINED NOVS2013 (
   IF DEFINED VS2013SP (
     SET YEARS=2013
   ) ELSE (