diff --git a/python/nav/alertengine/dispatchers/slack_dispatcher.py b/python/nav/alertengine/dispatchers/slack_dispatcher.py
index 93aabccb7d..4d582c1c71 100644
--- a/python/nav/alertengine/dispatchers/slack_dispatcher.py
+++ b/python/nav/alertengine/dispatchers/slack_dispatcher.py
@@ -19,6 +19,8 @@
 import json
 import time
 
+from django.core.validators import URLValidator
+from django.core.exceptions import ValidationError
 from urllib.request import Request, urlopen
 from urllib.error import HTTPError
 
@@ -86,4 +88,9 @@ def _is_still_backing_off_for(self, address):
 
     @staticmethod
     def is_valid_address(address):
+        validator = URLValidator()
+        try:
+            validator(address)
+        except ValidationError:
+            return False
         return True
diff --git a/python/nav/web/alertprofiles/forms.py b/python/nav/web/alertprofiles/forms.py
index 8a85f50da1..75105ac0a4 100644
--- a/python/nav/web/alertprofiles/forms.py
+++ b/python/nav/web/alertprofiles/forms.py
@@ -25,6 +25,7 @@
 from crispy_forms_foundation.layout import Layout, Row, Column, Field, Submit, HTML
 
 from nav.alertengine.dispatchers.email_dispatcher import Email
+from nav.alertengine.dispatchers.slack_dispatcher import Slack
 from nav.alertengine.dispatchers.sms_dispatcher import Sms
 
 from nav.models.profiles import MatchField, Filter, Expression, FilterGroup
@@ -118,6 +119,9 @@ def clean(self):
             elif type_.handler == 'email':
                 if not Email.is_valid_address(address):
                     error = 'Not a valid email address.'
+            elif type_.handler == 'slack':
+                if not Slack.is_valid_address(address):
+                    error = 'Not a valid absolute url.'
 
             if error:
                 self._errors['address'] = self.error_class([error])
diff --git a/tests/integration/web/alertprofiles_test.py b/tests/integration/web/alertprofiles_test.py
index 2276f95ef1..3e924cad6f 100644
--- a/tests/integration/web/alertprofiles_test.py
+++ b/tests/integration/web/alertprofiles_test.py
@@ -8,8 +8,13 @@
 from django.test.client import RequestFactory
 from django.urls import reverse
 from nav.compatibility import smart_str
-
-from nav.models.profiles import AlertProfile, Account, AlertPreference
+from nav.models.profiles import (
+    Account,
+    AlertAddress,
+    AlertPreference,
+    AlertProfile,
+    AlertSender,
+)
 from nav.web.alertprofiles.views import set_active_profile
 
 
@@ -171,6 +176,62 @@ def test_set_accountgroup_permissions_should_not_crash(db, client):
     assert response.status_code == 200
 
 
+def test_alertprofiles_add_slack_address_with_valid_url_should_succeed(client):
+    """Tests that a slack address with a valid absolute url can be added"""
+    valid_url = "https://example.com"
+    slack = AlertSender.objects.get(name=AlertSender.SLACK)
+    url = reverse("alertprofiles-address-save")
+    data = {
+        "address": valid_url,
+        "type": slack.pk,
+    }
+    response = client.post(url, data=data, follow=True)
+    assert response.status_code == 200
+    assert AlertAddress.objects.filter(
+        type=slack,
+        address=valid_url,
+    ).exists()
+    assert f"Saved address {valid_url}" in smart_str(response.content)
+
+
+def test_alertprofiles_add_slack_address_with_a_valid_but_not_absolute_url_should_fail(
+    client,
+):
+    """Tests that a slack address with a not valid url cannot be added"""
+    non_absolute_url = "www.example.com"
+    slack = AlertSender.objects.get(name=AlertSender.SLACK)
+    url = reverse("alertprofiles-address-save")
+    data = {
+        "address": non_absolute_url,
+        "type": slack.pk,
+    }
+    response = client.post(url, data=data, follow=True)
+    assert response.status_code == 200
+    assert not AlertAddress.objects.filter(
+        type=slack,
+        address=non_absolute_url,
+    ).exists()
+    assert "Not a valid absolute url." in smart_str(response.content)
+
+
+def test_alertprofiles_add_slack_address_with_non_valid_url_should_fail(client):
+    """Tests that a slack address with a not valid url cannot be added"""
+    invalid_url = "abc"
+    slack = AlertSender.objects.get(name=AlertSender.SLACK)
+    url = reverse("alertprofiles-address-save")
+    data = {
+        "address": invalid_url,
+        "type": slack.pk,
+    }
+    response = client.post(url, data=data, follow=True)
+    assert response.status_code == 200
+    assert not AlertAddress.objects.filter(
+        type=slack,
+        address=invalid_url,
+    ).exists()
+    assert "Not a valid absolute url." in smart_str(response.content)
+
+
 #
 # fixtures and helpers
 #