diff --git a/requires.py b/requires.py
index e756a43..7bb7be0 100644
--- a/requires.py
+++ b/requires.py
@@ -17,6 +17,8 @@ import json
 import socket
 import uuid
 
+from netaddr.core import AddrFormatError
+
 # the reactive framework unfortunately does not grok `import as` in conjunction
 # with decorators on class instance methods, so we have to revert to `from ...`
 # imports
@@ -215,7 +217,13 @@ class CephRBDMirrorRequires(Endpoint):
         """
         public_addr = self.all_joined_units.received['ceph-public-address']
         if public_addr:
-            return ch_ip.resolve_network_cidr(public_addr)
+            try:
+                return ch_ip.resolve_network_cidr(public_addr)
+            except AddrFormatError:
+                # LP#1898299 in some cases the netmask will be None, which
+                # leads to an AddrFormatError. In this case, we should return
+                # None
+                return None
 
     @property
     def cluster_network(self):
@@ -230,7 +238,13 @@ class CephRBDMirrorRequires(Endpoint):
         """
         cluster_addr = self.all_joined_units.received['ceph-cluster-address']
         if cluster_addr:
-            return ch_ip.resolve_network_cidr(cluster_addr)
+            try:
+                return ch_ip.resolve_network_cidr(cluster_addr)
+            except AddrFormatError:
+                # LP#1898299 in some cases the netmask will be None, which
+                # leads to an AddrFormatError. In this case, we should return
+                # None
+                return None
 
     @property
     def pools(self):
diff --git a/unit_tests/test_requires.py b/unit_tests/test_requires.py
index 64eafb2..f38c1b6 100644
--- a/unit_tests/test_requires.py
+++ b/unit_tests/test_requires.py
@@ -16,6 +16,8 @@ import json
 import mock
 import requires
 
+from netaddr.core import AddrFormatError
+
 import charms_openstack.test_utils as test_utils
 
 
@@ -201,6 +203,10 @@ class TestCephRBDMirrorRequires(test_utils.PatchHelper):
             'ceph-public-address')
         self.resolve_network_cidr.assert_called_once_with('192.0.2.1')
 
+        # Test no netmask condition
+        self.resolve_network_cidr.side_effect = AddrFormatError()
+        self.assertEqual(self.requires_class.public_network, None)
+
     def test_cluster_network(self):
         self.patch_requires_class('_all_joined_units')
         self._all_joined_units.received.__getitem__.return_value = '192.0.2.1'
@@ -211,6 +217,10 @@ class TestCephRBDMirrorRequires(test_utils.PatchHelper):
             'ceph-cluster-address')
         self.resolve_network_cidr.assert_called_once_with('192.0.2.1')
 
+        # Test no netmask condition
+        self.resolve_network_cidr.side_effect = AddrFormatError()
+        self.assertEqual(self.requires_class.cluster_network, None)
+
     def test_maybe_send_rq(self):
         self.patch_requires_class('_relations')
         relation = mock.MagicMock()