diff --git a/octodns/processor/arpa.py b/octodns/processor/arpa.py
index f680d7b..a2dfa0e 100644
--- a/octodns/processor/arpa.py
+++ b/octodns/processor/arpa.py
@@ -54,7 +54,7 @@ class AutoArpa(BaseProcessor):
         zone_name = zone.name
         n = len(zone_name) + 1
         for arpa, fqdns in self._records.items():
-            if arpa.endswith(zone_name):
+            if arpa.endswith(f'.{zone_name}'):
                 name = arpa[:-n]
                 fqdns = sorted(fqdns)
                 record = Record.new(
diff --git a/tests/test_octodns_processor_arpa.py b/tests/test_octodns_processor_arpa.py
index c2eacbc..b3baa43 100644
--- a/tests/test_octodns_processor_arpa.py
+++ b/tests/test_octodns_processor_arpa.py
@@ -201,3 +201,29 @@ class TestAutoArpa(TestCase):
         self.assertEqual('4.3.2.1.in-addr.arpa.', ptr.fqdn)
         self.assertEqual([record1.fqdn, record2.fqdn], ptr.values)
         self.assertEqual(3600, ptr.ttl)
+
+    def test_address_boundaries(self):
+        zone = Zone('unit.tests.', [])
+        record = Record.new(
+            zone, 'a', {'ttl': 32, 'type': 'A', 'value': '10.20.3.4'}
+        )
+        zone.add_record(record)
+        aa = AutoArpa('auto-arpa')
+        aa.process_source_zone(zone, [])
+        self.assertEqual(
+            {'4.3.20.10.in-addr.arpa.': {'a.unit.tests.'}}, aa._records
+        )
+
+        # matching zone
+        arpa = Zone('20.10.in-addr.arpa.', [])
+        aa.populate(arpa)
+        self.assertEqual(1, len(arpa.records))
+        (ptr,) = arpa.records
+        self.assertEqual('4.3.20.10.in-addr.arpa.', ptr.fqdn)
+        self.assertEqual(record.fqdn, ptr.value)
+        self.assertEqual(3600, ptr.ttl)
+
+        # non-matching boundary edge case
+        arpa = Zone('0.10.in-addr.arpa.', [])
+        aa.populate(arpa)
+        self.assertEqual(0, len(arpa.records))