diff --git a/tests/test_option_validator.py b/tests/test_option_validator.py
index 5ab0ab0..33c4153 100644
--- a/tests/test_option_validator.py
+++ b/tests/test_option_validator.py
@@ -598,6 +598,30 @@ async def test_validator_ip_in_network(config_type):
     assert not await list_sessions()
 
 
+@pytest.mark.asyncio
+async def test_validator_ip_in_network_incomplete(config_type):
+    a = NetworkOption('a', '')
+    b = NetmaskOption('b', '')
+    c = IPOption('c', '', validators=[Calculation(valid_in_network, Params((ParamSelfOption(), ParamOption(a, todict=True), ParamOption(b, todict=True))))])
+    d = IPOption('d', '', validators=[Calculation(valid_in_network, Params((ParamSelfOption(), ParamOption(a, todict=True), ParamOption(b, todict=True))), warnings_only=True)])
+    od = OptionDescription('od', '', [a, b, c, d])
+    warnings.simplefilter("always", ValueWarning)
+    async with await Config(od) as cfg:
+        cfg = await get_config(cfg, config_type)
+        #
+        await cfg.option('c').value.set('192.168.1.1')
+        #
+        await cfg.option('a').value.set('192.168.1.0')
+        await cfg.option('c').value.set('192.168.1.2')
+        await cfg.option('c').value.set('192.168.2.1')
+        #
+        await cfg.option('b').value.set('255.255.255.0')
+        await cfg.option('c').value.set('192.168.1.3')
+        with pytest.raises(ValueError):
+            await cfg.option('c').value.set('192.168.2.1')
+    assert not await list_sessions()
+
+
 @pytest.mark.asyncio
 async def test_validator_ip_in_network_cidr(config_type):
     a = NetworkOption('a', '', cidr=True)
@@ -621,6 +645,25 @@ async def test_validator_ip_in_network_cidr(config_type):
     assert not await list_sessions()
 
 
+@pytest.mark.asyncio
+async def test_validator_ip_in_network_cidr_incomplete(config_type):
+    a = NetworkOption('a', '', cidr=True)
+    c = IPOption('c', '', validators=[Calculation(valid_in_network, Params((ParamSelfOption(), ParamOption(a, todict=True))))])
+    d = IPOption('d', '', validators=[Calculation(valid_in_network, Params((ParamSelfOption(), ParamOption(a, todict=True))), warnings_only=True)])
+    od = OptionDescription('od', '', [a, c, d])
+    warnings.simplefilter("always", ValueWarning)
+    async with await Config(od) as cfg:
+        cfg = await get_config(cfg, config_type)
+        #
+        await cfg.option('c').value.set('192.168.1.1')
+        #
+        await cfg.option('a').value.set('192.168.1.0/24')
+        await cfg.option('c').value.set('192.168.1.2')
+        with pytest.raises(ValueError):
+            await cfg.option('c').value.set('192.168.2.1')
+    assert not await list_sessions()
+
+
 @pytest.mark.asyncio
 async def test_validator_ip_netmask_multi(config_type):
     a = IPOption('a', '', multi=True)
diff --git a/tiramisu/function.py b/tiramisu/function.py
index 23e0da1..f96ea5d 100644
--- a/tiramisu/function.py
+++ b/tiramisu/function.py
@@ -88,17 +88,21 @@ def valid_in_network(ip,
     else:
         network_value = network
         network_display_name = ''
-    if netmask is None:
+    if isinstance(netmask, dict):
+        netmask_value = netmask['value']
+        netmask_display_name = ' ({})'.format(netmask['name'])
+    else:
+        netmask_value = netmask
+        netmask_display_name = ''
+    if network_value is None:
+        return
+    if '/' in network_value:
         network_obj = ip_network('{0}'.format(network_value))
     else:
-        if isinstance(netmask, dict):
-            netmask_value = netmask['value']
-            netmask_display_name = ' ({})'.format(netmask['name'])
-        else:
-            netmask_value = netmask
-            netmask_display_name = ''
+        if netmask_value is None:
+            return
         network_obj = ip_network('{0}/{1}'.format(network_value,
-                                            netmask_value))
+                                                  netmask_value))
     if ip_interface(ip) not in network_obj:
         if netmask is None:
             msg = _('this IP is not in network {0}{1}').format(network_value,