diff --git a/tools/run_tests/run_tests_matrix.py b/tools/run_tests/run_tests_matrix.py
index 7d26b28..00680b0 100755
--- a/tools/run_tests/run_tests_matrix.py
+++ b/tools/run_tests/run_tests_matrix.py
@@ -209,16 +209,15 @@
                                 extra_args=extra_args,
                                 inner_jobs=inner_jobs)
 
-  # portability C on Windows
-  for arch in ['x86', 'x64']:
-    test_jobs += _generate_jobs(languages=['c'],
-                                configs=['dbg'],
-                                platforms=['windows'],
-                                arch=arch,
-                                compiler='default',
-                                labels=['portability', 'corelang'],
-                                extra_args=extra_args,
-                                inner_jobs=inner_jobs)
+  # portability C on Windows 64-bit (x86 is the default)
+  test_jobs += _generate_jobs(languages=['c'],
+                              configs=['dbg'],
+                              platforms=['windows'],
+                              arch='x64',
+                              compiler='default',
+                              labels=['portability', 'corelang'],
+                              extra_args=extra_args,
+                              inner_jobs=inner_jobs)
 
   # portability C++ on Windows
   # TODO(jtattermusch): some of the tests are failing, so we force --build_only
@@ -231,6 +230,17 @@
                               extra_args=extra_args + ['--build_only'],
                               inner_jobs=inner_jobs)
 
+  # portability C and C++ on Windows using VS2017 (build only)
+  # TODO(jtattermusch): some of the tests are failing, so we force --build_only
+  test_jobs += _generate_jobs(languages=['c', 'c++'],
+                              configs=['dbg'],
+                              platforms=['windows'],
+                              arch='x64',
+                              compiler='cmake_vs2017',
+                              labels=['portability', 'corelang'],
+                              extra_args=extra_args + ['--build_only'],
+                              inner_jobs=inner_jobs)
+
   # C and C++ with the c-ares DNS resolver on Linux
   test_jobs += _generate_jobs(languages=['c', 'c++'],
                               configs=['dbg'], platforms=['linux'],