diff --git a/tools/run_tests/run_tests.py b/tools/run_tests/run_tests.py
index 6ca5ef0208b2651411248a343bde9b6bb7822baa..6da6f42642612dd2e2953e8d2909e7f0f1962560 100755
--- a/tools/run_tests/run_tests.py
+++ b/tools/run_tests/run_tests.py
@@ -479,6 +479,7 @@ if platform.system() == 'Windows':
     return [
       jobset.JobSpec(['msbuild.exe', 
                       'vsprojects\\%s.sln' % target, 
+                      '/m',
                       '/p:Configuration=%s' % _WINDOWS_CONFIG[cfg]],
                       shell=True, timeout_seconds=30*60)
       for target in targets]