diff --git a/src/Microsoft.Health.Fhir.Shared.Api/Features/Filters/ParameterCompatibleFilter.cs b/src/Microsoft.Health.Fhir.Shared.Api/Features/Filters/ParameterCompatibleFilter.cs
index 35c91e0f85..4c2f2219c7 100644
--- a/src/Microsoft.Health.Fhir.Shared.Api/Features/Filters/ParameterCompatibleFilter.cs
+++ b/src/Microsoft.Health.Fhir.Shared.Api/Features/Filters/ParameterCompatibleFilter.cs
@@ -21,9 +21,15 @@ protected ParameterCompatibleFilter(bool allowParametersResource)
 
         protected Resource ParseResource(Resource resource)
         {
-            if (_allowParametersResource && resource.TypeName == KnownResourceTypes.Parameters)
+            if (_allowParametersResource && resource?.TypeName == KnownResourceTypes.Parameters)
             {
-                resource = ((Parameters)resource).Parameter.Find(param => param.Name.Equals("resource", StringComparison.OrdinalIgnoreCase)).Resource;
+                var parameters = (Parameters)resource;
+                var resourceParam = parameters.Parameter?.Find(param => param.Name.Equals("resource", StringComparison.OrdinalIgnoreCase));
+
+                if (resourceParam?.Resource != null)
+                {
+                    resource = resourceParam.Resource;
+                }
             }
 
             return resource;