diff --git a/agent/whois_ip_agent.py b/agent/whois_ip_agent.py
index a8f9fef..195c999 100644
--- a/agent/whois_ip_agent.py
+++ b/agent/whois_ip_agent.py
@@ -122,6 +122,12 @@ def _process_ip(self, message: m.Message, host: str) -> None:
             network = ipaddress.ip_network(host)
         else:
             version = message.data.get("version")
+            if version is None:
+                try:
+                    ip = ipaddress.ip_address(host)
+                    version = ip.version
+                except ValueError:
+                    raise ValueError(f"Invalid IP address: {host}")
             if version not in (4, 6):
                 raise ValueError(f"Incorrect ip version {version}.")
             elif version == 4 and int(mask) < IPV4_CIDR_LIMIT:
diff --git a/tests/whois_ip_agent_test.py b/tests/whois_ip_agent_test.py
index 5225b0a..e2cc01b 100644
--- a/tests/whois_ip_agent_test.py
+++ b/tests/whois_ip_agent_test.py
@@ -1,6 +1,7 @@
 """Unittests for WhoisIP agent."""
 
 from typing import List, Dict
+from unittest import mock
 
 import ipwhois
 import pytest
@@ -304,3 +305,45 @@ def testWhoisIP_whenIPHasNoASN_doesNotCrash(
     test_agent.process(scan_message_global_ipv4_with_mask32)
 
     assert len(agent_mock) == 0
+
+
+def testWhoisIP_withIPv4AndMaskButNoVersion_shouldHandleVersionCorrectly(
+    test_agent: whois_ip_agent.WhoisIPAgent,
+    agent_persist_mock: dict[str | bytes, str | bytes],
+) -> None:
+    """Test that process() handles the case when the version is None."""
+    message_data = {"host": "80.121.155.176", "mask": "29"}
+    test_message = message.Message.from_data(
+        selector="v3.asset.ip.v4",
+        data=message_data,
+    )
+
+    with mock.patch.object(
+        test_agent, "_redis_client"
+    ) as mock_redis_client, mock.patch.object(
+        test_agent, "add_ip_network"
+    ) as mock_add_ip_network, mock.patch.object(
+        test_agent, "start", mock.MagicMock()
+    ), mock.patch.object(test_agent, "run", mock.MagicMock()), mock.patch(
+        "agent.whois_ip_agent.WhoisIPAgent.main", mock.MagicMock()
+    ):
+        mock_redis_client.sismember.return_value = False
+
+        mock_add_ip_network.return_value = None
+
+        test_agent.process(test_message)
+
+        mock_add_ip_network.assert_called_once()
+
+
+def testWhoisIP_whenInvalidIPAddressIsProvided_raisesValueError(
+    test_agent: whois_ip_agent.WhoisIPAgent,
+    mocker: plugin.MockerFixture,
+) -> None:
+    """Test that a ValueError is raised when an invalid IP address is provided."""
+    input_selector = "v3.asset.ip.v4"
+    input_data = {"host": "invalid_ip", "mask": "24"}
+    ip_msg = message.Message.from_data(selector=input_selector, data=input_data)
+
+    with pytest.raises(ValueError, match="Invalid IP address: invalid_ip"):
+        test_agent.process(ip_msg)