diff --git a/bid_api/signals.py b/bid_api/signals.py
index 9508382..f7b7b40 100644
--- a/bid_api/signals.py
+++ b/bid_api/signals.py
@@ -21,7 +21,7 @@ USER_SAVE_INTERESTING_FIELDS = {
     "avatar",
     "date_deletion_requested",
     "confirmed_email_at",
-    # FIXME(anna): add nickname
+    "nickname",
 }
 WEBHOOK_TIMEOUT_SECS = 5
 
@@ -115,6 +115,7 @@ def modified_user_to_webhooks(sender, user: UserModel, **kwargs):
     # either database ID or email address.
     webhook_pre_save = getattr(user, "webhook_pre_save", {})
     old_email = webhook_pre_save.get("email")
+    old_nickname = webhook_pre_save.get("nickname") or ""
 
     # Map all falsey values to empty string for more consistent comparison later.
     # An empty avatar can be either '' or None.
@@ -144,11 +145,10 @@ def modified_user_to_webhooks(sender, user: UserModel, **kwargs):
         "email": user.email,
         "roles": sorted(user.public_roles()),
         "avatar_changed": old_avatar != cur_avatar,
-        "date_deletion_requested": user.date_deletion_requested.isoformat()
-        if user.date_deletion_requested else None,
-        "confirmed_email_at": user.confirmed_email_at.isoformat()
-        if user.confirmed_email_at else None,
-        # FIXME(anna): add nickname
+        "date_deletion_requested": isoformat(user.date_deletion_requested),
+        "confirmed_email_at": isoformat(user.confirmed_email_at),
+        "old_nickname": old_nickname,
+        "nickname": user.nickname,
     }
     json_payload = json.dumps(payload).encode()
 
@@ -156,3 +156,10 @@ def modified_user_to_webhooks(sender, user: UserModel, **kwargs):
     for hook in hooks:
         log.debug("Sending to %s, %s", hook, hook.url)
         hook.send(json_payload, sess)
+
+
+def isoformat(timestamp):
+    """None-safe timestamp.isoformat()."""
+    if not timestamp:
+        return None
+    return timestamp.isoformat()
diff --git a/bid_api/tests/test_webhooks.py b/bid_api/tests/test_webhooks.py
index cd0cc09..c870e99 100644
--- a/bid_api/tests/test_webhooks.py
+++ b/bid_api/tests/test_webhooks.py
@@ -63,6 +63,8 @@ class WebhookTest(WebhookBaseTest):
                 "avatar_changed": False,
                 "date_deletion_requested": None,
                 "confirmed_email_at": None,
+                "nickname": "",
+                "old_nickname": "",
             },
             payload,
         )
@@ -99,6 +101,56 @@ class WebhookTest(WebhookBaseTest):
                 "avatar_changed": False,
                 "date_deletion_requested": None,
                 "confirmed_email_at": None,
+                "nickname": "",
+                "old_nickname": "",
+            },
+            payload,
+        )
+
+    @responses.activate
+    def test_modify_user_nickname(self):
+        responses.add(responses.POST, self.HOOK_URL, json={"status": "success"}, status=200)
+
+        user = UserModel.objects.create_user("test@user.com", "123456")
+        user.nickname = "propellorolleporp"
+        user.save()
+
+        user.nickname = "maimuţă"
+        user.save()
+
+        self.assertTrue(user.webhook_user_modified)
+        self.assertEqual(2, len(responses.calls))
+
+        payload = json.loads(responses.calls[0].request.body)
+        self.assertEqual(
+            {
+                "id": user.id,
+                "old_email": "test@user.com",
+                "full_name": "",
+                "email": "test@user.com",
+                "roles": [],
+                "avatar_changed": False,
+                "date_deletion_requested": None,
+                "confirmed_email_at": None,
+                "nickname": "propellorolleporp",
+                "old_nickname": "",
+            },
+            payload,
+        )
+
+        payload = json.loads(responses.calls[1].request.body)
+        self.assertEqual(
+            {
+                "id": user.id,
+                "old_email": "test@user.com",
+                "full_name": "",
+                "email": "test@user.com",
+                "roles": [],
+                "avatar_changed": False,
+                "date_deletion_requested": None,
+                "confirmed_email_at": None,
+                "nickname": "maimuţă",
+                "old_nickname": "propellorolleporp",
             },
             payload,
         )
@@ -127,6 +179,8 @@ class WebhookTest(WebhookBaseTest):
                     "avatar_changed": True,
                     "date_deletion_requested": None,
                     "confirmed_email_at": None,
+                    "nickname": "",
+                    "old_nickname": "",
                 },
                 payload,
             )
@@ -170,6 +224,8 @@ class WebhookTest(WebhookBaseTest):
                 "roles": ["cloud_subscriber"],
                 "date_deletion_requested": None,
                 "confirmed_email_at": None,
+                "nickname": "",
+                "old_nickname": "",
             },
             payload,
         )
@@ -184,6 +240,8 @@ class WebhookTest(WebhookBaseTest):
                 "roles": [],
                 "date_deletion_requested": None,
                 "confirmed_email_at": None,
+                "nickname": "",
+                "old_nickname": "",
             },
             payload,
         )
@@ -214,6 +272,8 @@ class WebhookTest(WebhookBaseTest):
                 "avatar_changed": False,
                 "date_deletion_requested": "2020-12-31T23:02:03+00:00",
                 "confirmed_email_at": None,
+                "nickname": "",
+                "old_nickname": "",
             },
             payload,
         )
@@ -244,6 +304,8 @@ class WebhookTest(WebhookBaseTest):
                 "avatar_changed": False,
                 "date_deletion_requested": None,
                 "confirmed_email_at": "2021-01-01T02:05:06+00:00",
+                "nickname": "",
+                "old_nickname": "",
             },
             payload,
         )
@@ -275,6 +337,8 @@ class WebhookTest(WebhookBaseTest):
                 "roles": [],
                 "date_deletion_requested": None,
                 "confirmed_email_at": None,
+                "nickname": "",
+                "old_nickname": "",
             },
             payload,
             "The payload in the queue should be the POSTed JSON",
@@ -310,6 +374,8 @@ class WebhookTest(WebhookBaseTest):
                 "roles": [],
                 "date_deletion_requested": None,
                 "confirmed_email_at": None,
+                "nickname": "",
+                "old_nickname": "",
             },
             payload,
             "The payload in the queue should be the POSTed JSON",
@@ -353,6 +419,8 @@ class WebhookTest(WebhookBaseTest):
                 "roles": [],
                 "date_deletion_requested": None,
                 "confirmed_email_at": None,
+                "nickname": "",
+                "old_nickname": "",
             },
             payload,
         )
@@ -454,6 +522,8 @@ class WebhookTest(WebhookBaseTest):
                 "roles": [],
                 "date_deletion_requested": None,
                 "confirmed_email_at": None,
+                "nickname": "",
+                "old_nickname": "",
             },
             payload,
         )