diff --git a/metadata/metadata.go b/metadata/metadata.go
index 52070dbe..954c0f77 100644
--- a/metadata/metadata.go
+++ b/metadata/metadata.go
@@ -60,15 +60,21 @@ func encodeKeyValue(k, v string) (string, string) {
 
 // DecodeKeyValue returns the original key and value corresponding to the
 // encoded data in k, v.
+// If k is a binary header and v contains comma, v is split on comma before decoded,
+// and the decoded v will be joined with comma before returned.
 func DecodeKeyValue(k, v string) (string, string, error) {
 	if !strings.HasSuffix(k, binHdrSuffix) {
 		return k, v, nil
 	}
-	val, err := base64.StdEncoding.DecodeString(v)
-	if err != nil {
-		return "", "", err
+	vvs := strings.Split(v, ",")
+	for i, vv := range vvs {
+		val, err := base64.StdEncoding.DecodeString(vv)
+		if err != nil {
+			return "", "", err
+		}
+		vvs[i] = string(val)
 	}
-	return k, string(val), nil
+	return k, strings.Join(vvs, ","), nil
 }
 
 // MD is a mapping from metadata keys to values. Users should use the following
diff --git a/metadata/metadata_test.go b/metadata/metadata_test.go
index 02e6ba51..99e86820 100644
--- a/metadata/metadata_test.go
+++ b/metadata/metadata_test.go
@@ -74,6 +74,8 @@ func TestDecodeKeyValue(t *testing.T) {
 		{"a", "abc", "a", "abc", nil},
 		{"key-bin", "Zm9vAGJhcg==", "key-bin", "foo\x00bar", nil},
 		{"key-bin", "woA=", "key-bin", binaryValue, nil},
+		{"a", "abc,efg", "a", "abc,efg", nil},
+		{"key-bin", "Zm9vAGJhcg==,Zm9vAGJhcg==", "key-bin", "foo\x00bar,foo\x00bar", nil},
 	} {
 		k, v, err := DecodeKeyValue(test.kin, test.vin)
 		if k != test.kout || !reflect.DeepEqual(v, test.vout) || !reflect.DeepEqual(err, test.err) {