diff --git a/flac.go b/flac.go
index b0c0435..6b3da10 100644
--- a/flac.go
+++ b/flac.go
@@ -27,11 +27,6 @@ const (
 // ReadFLACTags reads FLAC metadata from the io.ReadSeeker, returning the resulting
 // metadata in a Metadata implementation, or non-nil error if there was a problem.
 func ReadFLACTags(r io.ReadSeeker) (Metadata, error) {
-	_, err := r.Seek(0, os.SEEK_SET)
-	if err != nil {
-		return nil, err
-	}
-
 	flac, err := readString(r, 4)
 	if err != nil {
 		return nil, err
diff --git a/id3v2.go b/id3v2.go
index d723a21..c3052ec 100644
--- a/id3v2.go
+++ b/id3v2.go
@@ -7,7 +7,6 @@ package tag
 import (
 	"fmt"
 	"io"
-	"os"
 	"strconv"
 	"strings"
 )
@@ -302,11 +301,6 @@ func (r *unsynchroniser) Read(p []byte) (int, error) {
 // ReadID3v2Tags parses ID3v2.{2,3,4} tags from the io.ReadSeeker into a Metadata, returning
 // non-nil error on failure.
 func ReadID3v2Tags(r io.ReadSeeker) (Metadata, error) {
-	_, err := r.Seek(0, os.SEEK_SET)
-	if err != nil {
-		return nil, err
-	}
-
 	h, err := readID3v2Header(r)
 	if err != nil {
 		return nil, err
diff --git a/mp4.go b/mp4.go
index 3458d27..84f241d 100644
--- a/mp4.go
+++ b/mp4.go
@@ -62,12 +62,8 @@ type metadataMP4 map[string]interface{}
 // ReadAtoms reads MP4 metadata atoms from the io.ReadSeeker into a Metadata, returning
 // non-nil error if there was a problem.
 func ReadAtoms(r io.ReadSeeker) (Metadata, error) {
-	_, err := r.Seek(0, os.SEEK_SET)
-	if err != nil {
-		return nil, err
-	}
 	m := make(metadataMP4)
-	err = m.readAtoms(r)
+	err := m.readAtoms(r)
 	return m, err
 }
 
diff --git a/ogg.go b/ogg.go
index 82a19ec..b10535b 100644
--- a/ogg.go
+++ b/ogg.go
@@ -20,11 +20,6 @@ const (
 // See http://www.xiph.org/vorbis/doc/Vorbis_I_spec.html
 // and http://www.xiph.org/ogg/doc/framing.html for details.
 func ReadOGGTags(r io.ReadSeeker) (Metadata, error) {
-	_, err := r.Seek(0, os.SEEK_SET)
-	if err != nil {
-		return nil, err
-	}
-
 	oggs, err := readString(r, 4)
 	if err != nil {
 		return nil, err
diff --git a/sum.go b/sum.go
index 421c4ef..789be46 100644
--- a/sum.go
+++ b/sum.go
@@ -17,6 +17,11 @@ func Sum(r io.ReadSeeker) (string, error) {
 		return "", err
 	}
 
+	_, err = r.Seek(-11, os.SEEK_CUR)
+	if err != nil {
+		return "", fmt.Errorf("could not seek back to original position: %v", err)
+	}
+
 	if string(b[4:11]) == "ftypM4A" {
 		return SumAtoms(r)
 	}
@@ -35,13 +40,8 @@ func Sum(r io.ReadSeeker) (string, error) {
 	return h, nil
 }
 
-// SumAll returns a checksum of the entire content.
+// SumAll returns a checksum of the content from the reader (until EOF).
 func SumAll(r io.ReadSeeker) (string, error) {
-	_, err := r.Seek(0, os.SEEK_SET)
-	if err != nil {
-		return "", fmt.Errorf("error seeking to 0: %v", err)
-	}
-
 	b, err := ioutil.ReadAll(r)
 	if err != nil {
 		return "", nil
@@ -52,14 +52,6 @@ func SumAll(r io.ReadSeeker) (string, error) {
 // SumAtoms constructs a checksum of MP4 audio file data provided by the io.ReadSeeker which is
 // metadata invariant.
 func SumAtoms(r io.ReadSeeker) (string, error) {
-	_, err := r.Seek(0, os.SEEK_SET)
-	if err != nil {
-		return "", fmt.Errorf("error seeking to 0: %v", err)
-	}
-	return sumAtoms(r)
-}
-
-func sumAtoms(r io.ReadSeeker) (string, error) {
 	for {
 		var size uint32
 		err := binary.Read(r, binary.BigEndian, &size)
@@ -85,7 +77,7 @@ func sumAtoms(r io.ReadSeeker) (string, error) {
 			fallthrough
 
 		case "moov", "udta", "ilst":
-			return sumAtoms(r)
+			return SumAtoms(r)
 
 		case "free":
 			_, err = r.Seek(int64(size-8), os.SEEK_CUR)
@@ -112,11 +104,6 @@ func sumAtoms(r io.ReadSeeker) (string, error) {
 // SumID3v1 constructs a checksum of MP3 audio file data (assumed to have ID3v1 tags) provided
 // by the io.ReadSeeker which is metadata invariant.
 func SumID3v1(r io.ReadSeeker) (string, error) {
-	_, err := r.Seek(0, os.SEEK_SET)
-	if err != nil {
-		return "", fmt.Errorf("error seeking to 0: %v", err)
-	}
-
 	b, err := ioutil.ReadAll(r)
 	if err != nil {
 		return "", err
@@ -131,11 +118,6 @@ func SumID3v1(r io.ReadSeeker) (string, error) {
 // SumID3v2 constructs a checksum of MP3 audio file data (assumed to have ID3v2 tags) provided by the
 // io.ReadSeeker which is metadata invariant.
 func SumID3v2(r io.ReadSeeker) (string, error) {
-	_, err := r.Seek(0, os.SEEK_SET)
-	if err != nil {
-		return "", fmt.Errorf("error seeking to 0: %v", err)
-	}
-
 	h, err := readID3v2Header(r)
 	if err != nil {
 		return "", fmt.Errorf("error reading ID3v2 header: %v", err)
diff --git a/tag.go b/tag.go
index 392916b..b52610e 100644
--- a/tag.go
+++ b/tag.go
@@ -7,7 +7,9 @@ package tag
 
 import (
 	"errors"
+	"fmt"
 	"io"
+	"os"
 )
 
 // ErrNoTagsFound is the error returned by ReadFrom when the metadata format
@@ -25,6 +27,11 @@ func ReadFrom(r io.ReadSeeker) (Metadata, error) {
 		return nil, err
 	}
 
+	_, err = r.Seek(-11, os.SEEK_CUR)
+	if err != nil {
+		return nil, fmt.Errorf("could not seek back to original position: %v", err)
+	}
+
 	switch {
 	case string(b[0:4]) == "fLaC":
 		return ReadFLACTags(r)