diff --git a/bin/build.py b/bin/build.py
index ee52a823..1d708c2e 100755
--- a/bin/build.py
+++ b/bin/build.py
@@ -184,7 +184,8 @@ def PositiveInt(string):
   detail.verify_msys_path.verify(msys_path)
   os.environ['PATH'] = "{};{}".format(msys_path, os.getenv('PATH'))
 
-if toolchain_entry.is_nmake:
+vs_ninja = toolchain_entry.is_ninja and toolchain_entry.vs_version
+if toolchain_entry.is_nmake or vs_ninja:
   os.environ = detail.get_nmake_environment.get(
       toolchain_entry.arch, toolchain_entry.vs_version
   )