diff --git a/xls/cfb/cfb.go b/xls/cfb/cfb.go
index 13ce1cd..f9daf44 100644
--- a/xls/cfb/cfb.go
+++ b/xls/cfb/cfb.go
@@ -292,7 +292,7 @@ func (d *doc) getStreamReader(sid uint32, size uint64) io.Reader {
 		panic("incomplete read")
 	}
 
-	return &sliceReader{data: streamData, offset: 0}
+	return &SliceReader{Data: streamData}
 }
 
 func (d *doc) getMiniStreamReader(sid uint32, size uint64) io.Reader {
@@ -341,5 +341,5 @@ func (d *doc) getMiniStreamReader(sid uint32, size uint64) io.Reader {
 		sid = d.minifat[sid]
 	}
 
-	return &sliceReader{data: streamData, offset: 0}
+	return &SliceReader{Data: streamData}
 }
diff --git a/xls/cfb/simple_test.go b/xls/cfb/simple_test.go
index 76e7030..3256e39 100644
--- a/xls/cfb/simple_test.go
+++ b/xls/cfb/simple_test.go
@@ -9,7 +9,7 @@ import (
 
 func TestHeader(t *testing.T) {
 	d := &doc{}
-	f, _ := os.Open("test.xls")
+	f, _ := os.Open("../testdata/test.xls")
 	err := d.load(f)
 	if err != nil {
 		t.Fatal(err)
@@ -18,7 +18,7 @@ func TestHeader(t *testing.T) {
 
 func TestHeader2(t *testing.T) {
 	d := &doc{}
-	f, _ := os.Open("test2.xls")
+	f, _ := os.Open("../testdata/test2.xls")
 	err := d.load(f)
 	if err != nil {
 		t.Fatal(err)
@@ -27,7 +27,7 @@ func TestHeader2(t *testing.T) {
 
 func TestHeader3(t *testing.T) {
 	d := &doc{}
-	f, _ := os.Open("test3.xls")
+	f, _ := os.Open("../testdata/test3.xls")
 	err := d.load(f)
 	if err != nil {
 		t.Fatal(err)
@@ -36,7 +36,7 @@ func TestHeader3(t *testing.T) {
 
 func TestHeader4(t *testing.T) {
 	d := &doc{}
-	f, _ := os.Open("test4.xls")
+	f, _ := os.Open("../testdata/test4.xls")
 	err := d.load(f)
 	if err != nil {
 		t.Fatal(err)
diff --git a/xls/cfb/slicereader.go b/xls/cfb/slicereader.go
index 4fd3994..6f637e4 100644
--- a/xls/cfb/slicereader.go
+++ b/xls/cfb/slicereader.go
@@ -1,25 +1,28 @@
 package cfb
 
-import "io"
+import (
+	"io"
+)
 
-type sliceReader struct {
-	data   [][]byte
-	offset uint
+type SliceReader struct {
+	Data   [][]byte
+	Index  uint
+	Offset uint
 }
 
-func (s *sliceReader) Read(b []byte) (int, error) {
-	var err error
-	if s.offset >= uint(len(s.data)) {
+func (s *SliceReader) Read(b []byte) (int, error) {
+	if s.Index >= uint(len(s.Data)) {
 		return 0, io.EOF
 	}
-	if len(b) < len(s.data[s.offset]) {
-		return 0, io.ErrShortBuffer
+	n := copy(b, s.Data[s.Index][s.Offset:])
+	if n > 0 {
+		s.Offset += uint(n)
+		if s.Offset == uint(len(s.Data[s.Index])) {
+			s.Offset = 0
+			s.Index++
+		}
+		return n, nil
 	}
 
-	n := copy(b, s.data[s.offset])
-	if n == 0 {
-		err = io.EOF
-	}
-	s.offset++
-	return n, err
+	return 0, io.EOF
 }