diff --git a/libsrc/utils/jsonschema/QJsonSchemaChecker.cpp b/libsrc/utils/jsonschema/QJsonSchemaChecker.cpp
index eea0dfa5..3eeea2ad 100644
--- a/libsrc/utils/jsonschema/QJsonSchemaChecker.cpp
+++ b/libsrc/utils/jsonschema/QJsonSchemaChecker.cpp
@@ -109,7 +109,7 @@ void QJsonSchemaChecker::validate(const QJsonValue & value, const QJsonObject &s
  		else if (attribute == "id")
  			; // references have already been collected
  		else if (attribute == "title" || attribute == "description"  || attribute == "default" || attribute == "format"
-			|| attribute == "defaultProperties" || attribute == "propertyOrder")
+			|| attribute == "defaultProperties" || attribute == "propertyOrder" || attribute == "append")
  			; // nothing to do.
 		else
 		{