diff --git a/src/Microsoft.Health.TaskManagement/JobInfoExtensions.cs b/src/Microsoft.Health.TaskManagement/JobInfoExtensions.cs
index 95491bddea..7aadb947c3 100644
--- a/src/Microsoft.Health.TaskManagement/JobInfoExtensions.cs
+++ b/src/Microsoft.Health.TaskManagement/JobInfoExtensions.cs
@@ -34,9 +34,9 @@ public static T DeserializeDefinition<T>(this JobInfo jobInfo)
     {
         EnsureArg.IsNotNull(jobInfo, nameof(jobInfo));
 
-        if (jobInfo.Definition == null)
+        if (jobInfo.Definition == null || jobInfo.Definition.Equals("null", StringComparison.OrdinalIgnoreCase))
         {
-            return default;
+            throw new ArgumentNullException(nameof(jobInfo));
         }
 
         return JsonConvert.DeserializeObject<T>(jobInfo.Definition);