diff --git a/object/convert.go b/object/convert.go
index 95fde3c..7099b4c 100644
--- a/object/convert.go
+++ b/object/convert.go
@@ -292,102 +292,26 @@ func (h *Header) FromGRPCMessage(m grpc.Message) error {
 
 	var err error
 
-	version := v.GetVersion()
-	if version == nil {
-		h.version = nil
-	} else {
-		if h.version == nil {
-			h.version = new(refs.Version)
-		}
-
-		err = h.version.FromGRPCMessage(version)
-		if err != nil {
-			return err
-		}
+	if err := h.fillVersion(v); err != nil {
+		return err
 	}
-
-	payloadHash := v.GetPayloadHash()
-	if payloadHash == nil {
-		h.payloadHash = nil
-	} else {
-		if h.payloadHash == nil {
-			h.payloadHash = new(refs.Checksum)
-		}
-
-		err = h.payloadHash.FromGRPCMessage(payloadHash)
-		if err != nil {
-			return err
-		}
+	if err := h.fillPayloadHash(v); err != nil {
+		return err
 	}
-
-	ownerID := v.GetOwnerId()
-	if ownerID == nil {
-		h.ownerID = nil
-	} else {
-		if h.ownerID == nil {
-			h.ownerID = new(refs.OwnerID)
-		}
-
-		err = h.ownerID.FromGRPCMessage(ownerID)
-		if err != nil {
-			return err
-		}
+	if err := h.fillOwnerID(v); err != nil {
+		return err
 	}
-
-	homoHash := v.GetHomomorphicHash()
-	if homoHash == nil {
-		h.homoHash = nil
-	} else {
-		if h.homoHash == nil {
-			h.homoHash = new(refs.Checksum)
-		}
-
-		err = h.homoHash.FromGRPCMessage(homoHash)
-		if err != nil {
-			return err
-		}
+	if err := h.fillHomomorphicHash(v); err != nil {
+		return err
 	}
-
-	cid := v.GetContainerId()
-	if cid == nil {
-		h.cid = nil
-	} else {
-		if h.cid == nil {
-			h.cid = new(refs.ContainerID)
-		}
-
-		err = h.cid.FromGRPCMessage(cid)
-		if err != nil {
-			return err
-		}
+	if err := h.fillContainerID(v); err != nil {
+		return err
 	}
-
-	sessionToken := v.GetSessionToken()
-	if sessionToken == nil {
-		h.sessionToken = nil
-	} else {
-		if h.sessionToken == nil {
-			h.sessionToken = new(session.Token)
-		}
-
-		err = h.sessionToken.FromGRPCMessage(sessionToken)
-		if err != nil {
-			return err
-		}
+	if err := h.fillSessionToken(v); err != nil {
+		return err
 	}
-
-	split := v.GetSplit()
-	if split == nil {
-		h.split = nil
-	} else {
-		if h.split == nil {
-			h.split = new(SplitHeader)
-		}
-
-		err = h.split.FromGRPCMessage(split)
-		if err != nil {
-			return err
-		}
+	if err := h.fillSplitHeader(v); err != nil {
+		return err
 	}
 
 	h.attr, err = AttributesFromGRPC(v.GetAttributes())
@@ -402,6 +326,97 @@ func (h *Header) FromGRPCMessage(m grpc.Message) error {
 	return nil
 }
 
+func (h *Header) fillVersion(v *object.Header) error {
+	version := v.GetVersion()
+	if version == nil {
+		h.version = nil
+		return nil
+	}
+
+	if h.version == nil {
+		h.version = new(refs.Version)
+	}
+	return h.version.FromGRPCMessage(version)
+}
+
+func (h *Header) fillPayloadHash(v *object.Header) error {
+	payloadHash := v.GetPayloadHash()
+	if payloadHash == nil {
+		h.payloadHash = nil
+		return nil
+	}
+
+	if h.payloadHash == nil {
+		h.payloadHash = new(refs.Checksum)
+	}
+	return h.payloadHash.FromGRPCMessage(payloadHash)
+}
+
+func (h *Header) fillOwnerID(v *object.Header) error {
+	ownerID := v.GetOwnerId()
+	if ownerID == nil {
+		h.ownerID = nil
+		return nil
+	}
+
+	if h.ownerID == nil {
+		h.ownerID = new(refs.OwnerID)
+	}
+	return h.ownerID.FromGRPCMessage(ownerID)
+}
+
+func (h *Header) fillHomomorphicHash(v *object.Header) error {
+	homoHash := v.GetHomomorphicHash()
+	if homoHash == nil {
+		h.homoHash = nil
+		return nil
+	}
+
+	if h.homoHash == nil {
+		h.homoHash = new(refs.Checksum)
+	}
+	return h.homoHash.FromGRPCMessage(homoHash)
+}
+
+func (h *Header) fillContainerID(v *object.Header) error {
+	cid := v.GetContainerId()
+	if cid == nil {
+		h.cid = nil
+		return nil
+	}
+
+	if h.cid == nil {
+		h.cid = new(refs.ContainerID)
+	}
+	return h.cid.FromGRPCMessage(cid)
+}
+
+func (h *Header) fillSessionToken(v *object.Header) error {
+	sessionToken := v.GetSessionToken()
+	if sessionToken == nil {
+		h.sessionToken = nil
+		return nil
+	}
+
+	if h.sessionToken == nil {
+		h.sessionToken = new(session.Token)
+	}
+	return h.sessionToken.FromGRPCMessage(sessionToken)
+}
+
+func (h *Header) fillSplitHeader(v *object.Header) error {
+	split := v.GetSplit()
+	if split == nil {
+		h.split = nil
+		return nil
+	}
+
+	if h.split == nil {
+		h.split = new(SplitHeader)
+	}
+	return h.split.FromGRPCMessage(split)
+}
+
 func (h *HeaderWithSignature) ToGRPCMessage() grpc.Message {
 	var m *object.HeaderWithSignature