diff --git a/object/grpc/service.go b/object/grpc/service.go
index 74dc168..44b5f4a 100644
--- a/object/grpc/service.go
+++ b/object/grpc/service.go
@@ -109,7 +109,7 @@ func (m *PutRequest_Body_Init) SetHeader(v *Header) {
 }
 
 // SetCopiesNumber sets number of the copies to save.
-func (m *PutRequest_Body_Init) SetCopiesNumber(v []uint32) {
+func (m *PutRequest_Body_Init) SetCopiesNumber(v uint32) {
 	m.CopiesNumber = v
 }
 
diff --git a/object/grpc/service.pb.go b/object/grpc/service.pb.go
index 6ba4090..207b0b0 100644
Binary files a/object/grpc/service.pb.go and b/object/grpc/service.pb.go differ
diff --git a/object/marshal.go b/object/marshal.go
index 7a89b97..b918e69 100644
--- a/object/marshal.go
+++ b/object/marshal.go
@@ -516,7 +516,7 @@ func (r *PutObjectPartInit) StableMarshal(buf []byte) []byte {
 	offset += proto.NestedStructureMarshal(putReqInitObjectIDField, buf[offset:], r.id)
 	offset += proto.NestedStructureMarshal(putReqInitSignatureField, buf[offset:], r.sig)
 	offset += proto.NestedStructureMarshal(putReqInitHeaderField, buf[offset:], r.hdr)
-	proto.RepeatedUInt32Marshal(putReqInitCopiesNumField, buf[offset:], r.copyNum)
+	proto.UInt32Marshal(putReqInitCopiesNumField, buf[offset:], r.copyNum)
 
 	return buf
 }
@@ -529,9 +529,7 @@ func (r *PutObjectPartInit) StableSize() (size int) {
 	size += proto.NestedStructureSize(putReqInitObjectIDField, r.id)
 	size += proto.NestedStructureSize(putReqInitSignatureField, r.sig)
 	size += proto.NestedStructureSize(putReqInitHeaderField, r.hdr)
-
-	arrSize, _ := proto.RepeatedUInt32Size(putReqInitCopiesNumField, r.copyNum)
-	size += arrSize
+	size += proto.UInt32Size(putReqInitCopiesNumField, r.copyNum)
 
 	return size
 }
diff --git a/object/test/generate.go b/object/test/generate.go
index 32d7a3c..0816ffc 100644
--- a/object/test/generate.go
+++ b/object/test/generate.go
@@ -216,7 +216,7 @@ func GeneratePutObjectPartInit(empty bool) *object.PutObjectPartInit {
 	m := new(object.PutObjectPartInit)
 
 	if !empty {
-		m.SetCopiesNumber([]uint32{234})
+		m.SetCopiesNumber(234)
 		m.SetObjectID(refstest.GenerateObjectID(false))
 	}
 
diff --git a/object/types.go b/object/types.go
index a40de57..f076b74 100644
--- a/object/types.go
+++ b/object/types.go
@@ -128,7 +128,7 @@ type PutObjectPartInit struct {
 
 	hdr *Header
 
-	copyNum []uint32
+	copyNum uint32
 }
 
 type PutObjectPartChunk struct {
@@ -894,15 +894,15 @@ func (r *PutObjectPartInit) SetHeader(v *Header) {
 	r.hdr = v
 }
 
-func (r *PutObjectPartInit) GetCopiesNumber() []uint32 {
+func (r *PutObjectPartInit) GetCopiesNumber() uint32 {
 	if r != nil {
 		return r.copyNum
 	}
 
-	return nil
+	return 0
 }
 
-func (r *PutObjectPartInit) SetCopiesNumber(v []uint32) {
+func (r *PutObjectPartInit) SetCopiesNumber(v uint32) {
 	r.copyNum = v
 }