diff --git a/tools/run_tests/run_tests.py b/tools/run_tests/run_tests.py
index 6b84daea544b0047daeb9f571f9ebbf4c8fbc160..486173c045dd3b9a6413eaa9f88893a151717f8f 100755
--- a/tools/run_tests/run_tests.py
+++ b/tools/run_tests/run_tests.py
@@ -478,7 +478,8 @@ class CSharpLanguage(object):
       _check_compiler(self.args.compiler, ['default'])
       if self.platform == 'mac':
         # On Mac, official distribution of mono is 32bit.
-        self._make_options = ['EMBED_OPENSSL=true', 'EMBED_ZLIB=true',
+        # TODO(jtattermusch): EMBED_ZLIB=true currently breaks the mac build
+        self._make_options = ['EMBED_OPENSSL=true'
                               'CFLAGS=-arch i386', 'LDFLAGS=-arch i386']
       else:
         self._make_options = ['EMBED_OPENSSL=true', 'EMBED_ZLIB=true']