diff --git a/ryu/services/protocols/vrrp/__init__.py b/ryu/services/protocols/vrrp/__init__.py
index 340a4230..da23e668 100644
--- a/ryu/services/protocols/vrrp/__init__.py
+++ b/ryu/services/protocols/vrrp/__init__.py
@@ -13,3 +13,6 @@
 # implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
+
+import ryu.services.protocols.vrrp.monitor_linux
+import ryu.services.protocols.vrrp.monitor_openflow