diff --git a/client.go b/client.go
index 04fa8299..4d90091a 100644
--- a/client.go
+++ b/client.go
@@ -129,6 +129,11 @@ func (c *Client) Do(r *Request) (*Response, error) {
 		return nil, err
 	}
 	req.Header.Set("User-Agent", DefaultUserAgent) // Maybe https://codereview.appspot.com/7532043.
+	for name, values := range r.ExtraHeaders {
+		for _, value := range values {
+			req.Header.Add(name, value)
+		}
+	}
 
 	resp, err := c.Doer.Do(req)
 	if err != nil {
diff --git a/cmd/metha-sync/main.go b/cmd/metha-sync/main.go
index 58af7019..adbcaf36 100644
--- a/cmd/metha-sync/main.go
+++ b/cmd/metha-sync/main.go
@@ -4,12 +4,17 @@ import (
 	"flag"
 	"fmt"
 	"io/ioutil"
+	"net/http"
 	"os"
+	"strings"
 
 	"github.com/miku/metha"
+	"github.com/miku/metha/xflag"
 	log "github.com/sirupsen/logrus"
 )
 
+var extraHeaders xflag.Array
+
 func main() {
 
 	format := flag.String("format", "oai_dc", "metadata format")
@@ -31,6 +36,8 @@ func main() {
 	logFile := flag.String("log", "", "filename to log to")
 	logStderr := flag.Bool("log-errors-to-stderr", false, "Log errors and warnings to STDERR. If -log or -q are not given, write full log to STDOUT")
 
+	flag.Var(&extraHeaders, "H", `extra HTTP header to pass to requests (repeatable); e.g. -H "token: 123" `)
+
 	flag.Parse()
 
 	if *version {
@@ -83,6 +90,15 @@ func main() {
 		log.AddHook(metha.NewCopyHook(os.Stderr))
 	}
 
+	var extra http.Header
+	for _, s := range extraHeaders {
+		parts := strings.SplitN(s, ":", 1)
+		if len(parts) != 2 {
+			log.Fatal(`extra headers notation is "Some-Key: Some-Value"`)
+		}
+		extra.Add(parts[0], parts[1])
+	}
+
 	harvest, err := metha.NewHarvest(baseURL)
 	if err != nil {
 		log.Fatal(err)
@@ -103,6 +119,7 @@ func main() {
 	harvest.IgnoreHTTPErrors = *ignoreHTTPErrors
 	harvest.SuppressFormatParameter = *suppressFormatParameter
 	harvest.DailyInterval = *daily
+	harvest.ExtraHeaders = extra
 
 	log.Printf("harvest: %+v", harvest)
 
diff --git a/harvest.go b/harvest.go
index d238634c..f6760231 100644
--- a/harvest.go
+++ b/harvest.go
@@ -7,6 +7,7 @@ import (
 	"fmt"
 	"io/ioutil"
 	"math/rand"
+	"net/http"
 	"os"
 	"os/signal"
 	"path/filepath"
@@ -63,6 +64,7 @@ type Harvest struct {
 	MaxEmptyResponses          int
 	SuppressFormatParameter    bool
 	DailyInterval              bool
+	ExtraHeaders               http.Header
 
 	// XXX: Lazy via sync.Once?
 	Identify *Identify
@@ -312,6 +314,7 @@ func (h *Harvest) runInterval(iv Interval) error {
 			ResumptionToken:         token,
 			CleanBeforeDecode:       h.CleanBeforeDecode,
 			SuppressFormatParameter: h.SuppressFormatParameter,
+			ExtraHeaders:            h.ExtraHeaders,
 		}
 
 		var filedate string
@@ -416,7 +419,11 @@ func (h *Harvest) earliestDate() (time.Time, error) {
 
 // identify runs an OAI identify request and caches the result.
 func (h *Harvest) identify() error {
-	req := Request{Verb: "Identify", BaseURL: h.BaseURL}
+	req := Request{
+		Verb:         "Identify",
+		BaseURL:      h.BaseURL,
+		ExtraHeaders: h.ExtraHeaders,
+	}
 
 	c := CreateClient(30*time.Second, 2)
 
diff --git a/request.go b/request.go
index a2c82645..293e5494 100644
--- a/request.go
+++ b/request.go
@@ -4,6 +4,7 @@ import (
 	"bytes"
 	"errors"
 	"fmt"
+	"net/http"
 	"net/url"
 	"sort"
 	"strings"
@@ -30,6 +31,7 @@ type Request struct {
 	ResumptionToken         string
 	CleanBeforeDecode       bool
 	SuppressFormatParameter bool
+	ExtraHeaders            http.Header
 }
 
 // Values enhances the builtin url.Values.
diff --git a/xflag/flag.go b/xflag/flag.go
new file mode 100644
index 00000000..c4aa5ecd
--- /dev/null
+++ b/xflag/flag.go
@@ -0,0 +1,25 @@
+// Package xflag add an additional flag type Array for repeated string flags.
+//
+//   var f xflag.Array
+//   flag.Var(&f, "r", "some repeatable flag")
+//
+//   flag.Parse()                // $ command -r a -r b -r c
+//   for _, v := range f { ... } // []string{"a", "b", "c"}
+//
+package xflag
+
+import "strings"
+
+// ArrayFlags allows to store lists of flag values.
+type Array []string
+
+// String representation.
+func (f *Array) String() string {
+	return strings.Join(*f, ", ")
+}
+
+// Set appends a value.
+func (f *Array) Set(value string) error {
+	*f = append(*f, value)
+	return nil
+}