diff --git a/migrator/migrator.go b/migrator/migrator.go
index 5de820a8..084d430f 100644
--- a/migrator/migrator.go
+++ b/migrator/migrator.go
@@ -381,7 +381,7 @@ func (m Migrator) MigrateColumn(value interface{}, field *schema.Field, columnTy
 
 	// check precision
 	if precision, _, ok := columnType.DecimalSize(); ok && int64(field.Precision) != precision {
-		if strings.Contains(fullDataType, fmt.Sprint(field.Precision)) {
+		if strings.Contains(m.DataTypeOf(field), fmt.Sprint(field.Precision)) {
 			alterColumn = true
 		}
 	}