diff --git a/zerver/tests/test_push_notifications.py b/zerver/tests/test_push_notifications.py
index 3057cb9b00..a8c299fffe 100644
--- a/zerver/tests/test_push_notifications.py
+++ b/zerver/tests/test_push_notifications.py
@@ -2470,6 +2470,14 @@ class PushBouncerSignupTest(ZulipTestCase):
         result = self.client_post("/api/v1/remotes/server/register", request)
         self.assert_json_error(result, "Invalid UUID")
 
+        # This looks mostly like a proper UUID, but isn't actually a valid UUIDv4,
+        # which makes it slip past a basic validation via initializing uuid.UUID with it.
+        # Thus we should test this scenario separately.
+        zulip_org_id = "18cedb98-5222-5f34-50a9-fc418e1ba972"
+        request["zulip_org_id"] = zulip_org_id
+        result = self.client_post("/api/v1/remotes/server/register", request)
+        self.assert_json_error(result, "Invalid UUID")
+
     def test_push_signup_success(self) -> None:
         zulip_org_id = str(uuid.uuid4())
         zulip_org_key = get_random_string(64)
diff --git a/zilencer/views.py b/zilencer/views.py
index 432679727b..de8f1f081c 100644
--- a/zilencer/views.py
+++ b/zilencer/views.py
@@ -53,7 +53,13 @@ def validate_entity(entity: Union[UserProfile, RemoteZulipServer]) -> RemoteZuli
 
 def validate_uuid(uuid: str) -> None:
     try:
-        UUID(uuid, version=4)
+        uuid_object = UUID(uuid, version=4)
+        # The UUID initialization under some circumstances will modify the uuid
+        # string to create a valid UUIDv4, instead of raising a ValueError.
+        # The submitted uuid needing to be modified means it's invalid, so
+        # we need to check for that condition.
+        if str(uuid_object) != uuid:
+            raise ValidationError(err_("Invalid UUID"))
     except ValueError:
         raise ValidationError(err_("Invalid UUID"))