diff --git a/tools/testing/kunit/kunit_tool_test.py b/tools/testing/kunit/kunit_tool_test.py
index 22f16e6..cba9775 100755
--- a/tools/testing/kunit/kunit_tool_test.py
+++ b/tools/testing/kunit/kunit_tool_test.py
@@ -174,6 +174,7 @@
 		kunit.main(['run'], self.linux_source_mock)
 		assert self.linux_source_mock.build_reconfig.call_count == 1
 		assert self.linux_source_mock.run_kernel.call_count == 1
+		self.linux_source_mock.run_kernel.assert_called_once_with(build_dir='', timeout=300)
 		self.print_mock.assert_any_call(StrContains('Testing complete.'))
 
 	def test_run_passes_args_fail(self):
@@ -202,5 +203,12 @@
 		self.linux_source_mock.run_kernel.assert_called_once_with(build_dir='', timeout=timeout)
 		self.print_mock.assert_any_call(StrContains('Testing complete.'))
 
+	def test_run_builddir(self):
+		build_dir = '.kunit'
+		kunit.main(['run', '--build_dir', build_dir], self.linux_source_mock)
+		assert self.linux_source_mock.build_reconfig.call_count == 1
+		self.linux_source_mock.run_kernel.assert_called_once_with(build_dir=build_dir, timeout=300)
+		self.print_mock.assert_any_call(StrContains('Testing complete.'))
+
 if __name__ == '__main__':
 	unittest.main()