diff --git a/tools/run_tests/run_tests.py b/tools/run_tests/run_tests.py
index d3819c08840f761a1cb1c94e18cf9f34d255b59a..2a80706e6a8cf6df8e7407a11149f028151c0044 100755
--- a/tools/run_tests/run_tests.py
+++ b/tools/run_tests/run_tests.py
@@ -509,6 +509,8 @@ class CSharpLanguage(object):
       _check_compiler(self.args.compiler, ['default', 'coreclr'])
       if self.platform == 'linux' and self.args.compiler == 'coreclr':
         self._docker_distro = 'coreclr'
+      else:
+        self._docker_distro = 'jessie'
 
       if self.platform == 'mac':
         # TODO(jtattermusch): EMBED_ZLIB=true currently breaks the mac build