diff --git a/workitem/enum_type.go b/workitem/enum_type.go
index 1a1701dc00..98ff33b88b 100644
--- a/workitem/enum_type.go
+++ b/workitem/enum_type.go
@@ -162,8 +162,10 @@ func (t EnumType) ConvertFromModel(value interface{}) (interface{}, error) {
 	if err != nil {
 		return nil, fmt.Errorf("error converting enum value: %s", err.Error())
 	}
-	if !contains(t.Values, converted) {
-		return nil, fmt.Errorf("value: %+v (%[1]T) is not part of allowed enum values: %+v", value, t.Values)
+	if value != nil {
+		if !contains(t.Values, converted) {
+			return nil, fmt.Errorf("value: %+v (%[1]T) is not part of allowed enum values: %+v", value, t.Values)
+		}
 	}
 	return converted, nil
 }