diff --git a/changed_fields.go b/changed_fields.go
index 405f966..41e0fe6 100644
--- a/changed_fields.go
+++ b/changed_fields.go
@@ -27,6 +27,10 @@ func (cf ChangedFields) Changed(field string) bool {
 }
 
 func (cf *ChangedFields) SetChanged(fields ...string) {
+	if cf.fieldNames == nil {
+		cf.fieldNames = make(map[string]struct{})
+	}
+
 	for _, field := range fields {
 		cf.fieldNames[field] = struct{}{}
 	}
@@ -35,3 +39,7 @@ func (cf *ChangedFields) SetChanged(fields ...string) {
 func (cf ChangedFields) Empty() bool {
 	return len(cf.fieldNames) == 0
 }
+
+func (cf ChangedFields) IsNil() bool {
+	return cf.fieldNames == nil
+}
diff --git a/fields_mask.go b/fields_mask.go
index 2179582..151bf09 100644
--- a/fields_mask.go
+++ b/fields_mask.go
@@ -52,6 +52,18 @@ func (fm FieldsMask) IsFilled() bool {
 	return false
 }
 
+func (fm *FieldsMask) Reset() {
+	for i := range fm.parts {
+		fm.parts[i] = 0
+	}
+}
+
+func (fm *FieldsMask) SetChangedAll() {
+	for i := range fm.parts {
+		fm.parts[i] = 1<<64 - 1
+	}
+}
+
 func (fm FieldsMask) partIndex(index uint64) uint64 {
 	return index / FieldsMaskPartBitSize
 }