diff --git a/callbacks/create.go b/callbacks/create.go
index a9cbddf9..f0b78139 100644
--- a/callbacks/create.go
+++ b/callbacks/create.go
@@ -304,7 +304,7 @@ func ConvertToCreateValues(stmt *gorm.Statement) (values clause.Values) {
 					if field := stmt.Schema.LookUpField(column.Name); field != nil {
 						if v, ok := selectColumns[field.DBName]; (ok && v) || (!ok && !restricted) {
 							if !field.PrimaryKey && (!field.HasDefaultValue || field.DefaultValueInterface != nil ||
-								strings.ToUpper(field.DefaultValue) == "NULL") && field.AutoCreateTime == 0 {
+								strings.EqualFold(field.DefaultValue, "NULL")) && field.AutoCreateTime == 0 {
 								if field.AutoUpdateTime > 0 {
 									assignment := clause.Assignment{Column: clause.Column{Name: field.DBName}, Value: curTime}
 									switch field.AutoUpdateTime {