diff --git a/tools/run_tests/run_tests.py b/tools/run_tests/run_tests.py
index 6e20da1dcef7e0a9a26f6f7ce7918cd42f5831ed..71bb7b12db061b45e620d0739e628aa0d3b64a4c 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=-m32', 'LDFLAGS=-m32']
       else:
         self._make_options = ['EMBED_OPENSSL=true', 'EMBED_ZLIB=true']