diff --git a/CHANGELOG.md b/CHANGELOG.md
index 72545e26..d6993bb6 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,4 +1,6 @@
 # Change log
+## Unreleased
+* Fixed bug where if the range or threshold of an alert is zero the alert type validation fails.
 ## [v2.1.1](https://github.com/simvue-io/client/releases/tag/v2.1.1) - 2025-04-25
 * Changed from CO2 Signal to ElectricityMaps
 * Fixed a number of bugs in how offline mode is handled with emissions
diff --git a/simvue/api/objects/alert/fetch.py b/simvue/api/objects/alert/fetch.py
index 05cc132d..cf7dae47 100644
--- a/simvue/api/objects/alert/fetch.py
+++ b/simvue/api/objects/alert/fetch.py
@@ -131,8 +131,9 @@ def get(
                     _id,
                     UserAlert(_read_only=True, identifier=_id, _local=True, **_entry),
                 )
-            elif _entry["source"] == "metrics" and _entry.get("alert", {}).get(
-                "threshold"
+            elif (
+                _entry["source"] == "metrics"
+                and _entry.get("alert", {}).get("threshold") is not None
             ):
                 yield (
                     _id,
@@ -140,8 +141,9 @@ def get(
                         _local=True, _read_only=True, identifier=_id, **_entry
                     ),
                 )
-            elif _entry["source"] == "metrics" and _entry.get("alert", {}).get(
-                "range_low"
+            elif (
+                _entry["source"] == "metrics"
+                and _entry.get("alert", {}).get("range_low") is not None
             ):
                 yield (
                     _id,