4 files changed, 51 insertions, 5 deletions
diff --git a/plumbing/format/diff/unified_encoder.go b/plumbing/format/diff/unified_encoder.go
index a4ff7ab..cf2a34b 100644
--- a/plumbing/format/diff/unified_encoder.go
+++ b/plumbing/format/diff/unified_encoder.go
@@ -2,7 +2,6 @@ package diff
 
 import (
 	"bytes"
-	"errors"
 	"fmt"
 	"io"
 	"strings"
@@ -45,8 +44,6 @@ const (
 	DefaultContextLines = 3
 )
 
-var ErrBothFilesEmpty = errors.New("both files are empty")
-
 // UnifiedEncoder encodes an unified diff into the provided Writer.
 // There are some unsupported features:
 //     - Similarity index for renames
@@ -106,7 +103,7 @@ func (e *UnifiedEncoder) printMessage(message string) {
 func (e *UnifiedEncoder) header(from, to File, isBinary bool) error {
 	switch {
 	case from == nil && to == nil:
-		return ErrBothFilesEmpty
+		return nil
 	case from != nil && to != nil:
 		hashEquals := from.Hash() == to.Hash()
 
diff --git a/plumbing/format/diff/unified_encoder_test.go b/plumbing/format/diff/unified_encoder_test.go
index b832920..6e12070 100644
--- a/plumbing/format/diff/unified_encoder_test.go
+++ b/plumbing/format/diff/unified_encoder_test.go
@@ -20,7 +20,7 @@ func (s *UnifiedEncoderTestSuite) TestBothFilesEmpty(c *C) {
 	buffer := bytes.NewBuffer(nil)
 	e := NewUnifiedEncoder(buffer, 1)
 	err := e.Encode(testPatch{filePatches: []testFilePatch{{}}})
-	c.Assert(err, Equals, ErrBothFilesEmpty)
+	c.Assert(err, IsNil)
 }
 
 func (s *UnifiedEncoderTestSuite) TestBinaryFile(c *C) {
diff --git a/plumbing/object/patch.go b/plumbing/object/patch.go
index a920631..aa96a96 100644
--- a/plumbing/object/patch.go
+++ b/plumbing/object/patch.go
@@ -271,6 +271,11 @@ func getFileStatsFromFilePatches(filePatches []fdiff.FilePatch) FileStats {
 	var fileStats FileStats
 
 	for _, fp := range filePatches {
+		// ignore empty patches (binary files, submodule refs updates)
+		if len(fp.Chunks()) == 0 {
+			continue
+		}
+
 		cs := FileStat{}
 		from, to := fp.Files()
 		if from == nil {
diff --git a/plumbing/object/patch_test.go b/plumbing/object/patch_test.go
new file mode 100644
index 0000000..8eb65ec
--- /dev/null
+++ b/plumbing/object/patch_test.go
@@ -0,0 +1,44 @@
+package object
+
+import (
+	. "gopkg.in/check.v1"
+	fixtures "gopkg.in/src-d/go-git-fixtures.v3"
+	"gopkg.in/src-d/go-git.v4/plumbing"
+	"gopkg.in/src-d/go-git.v4/storage/filesystem"
+)
+
+type PatchSuite struct {
+	BaseObjectsSuite
+}
+
+var _ = Suite(&PatchSuite{})
+
+func (s *PatchSuite) TestStatsWithSubmodules(c *C) {
+	storer, err := filesystem.NewStorage(
+		fixtures.ByURL("https://github.com/git-fixtures/submodule.git").One().DotGit())
+
+	commit, err := GetCommit(storer, plumbing.NewHash("b685400c1f9316f350965a5993d350bc746b0bf4"))
+
+	tree, err := commit.Tree()
+	c.Assert(err, IsNil)
+
+	e, err := tree.entry("basic")
+	c.Assert(err, IsNil)
+
+	ch := &Change{
+		From: ChangeEntry{
+			Name:      "basic",
+			Tree:      tree,
+			TreeEntry: *e,
+		},
+		To: ChangeEntry{
+			Name:      "basic",
+			Tree:      tree,
+			TreeEntry: *e,
+		},
+	}
+
+	p, err := getPatch("", ch)
+	c.Assert(err, IsNil)
+	c.Assert(p, NotNil)
+}