diff --git a/message_xdr.go b/message_xdr.go
index 324125ea4..948e63c32 100644
--- a/message_xdr.go
+++ b/message_xdr.go
@@ -44,20 +44,28 @@ func (o IndexMessage) EncodeXDR(w io.Writer) (int, error) {
 	return o.encodeXDR(xw)
 }
 
-func (o IndexMessage) MarshalXDR() []byte {
+func (o IndexMessage) MarshalXDR() ([]byte, error) {
 	return o.AppendXDR(make([]byte, 0, 128))
 }
 
-func (o IndexMessage) AppendXDR(bs []byte) []byte {
+func (o IndexMessage) MustMarshalXDR() []byte {
+	bs, err := o.MarshalXDR()
+	if err != nil {
+		panic(err)
+	}
+	return bs
+}
+
+func (o IndexMessage) AppendXDR(bs []byte) ([]byte, error) {
 	var aw = xdr.AppendWriter(bs)
 	var xw = xdr.NewWriter(&aw)
-	o.encodeXDR(xw)
-	return []byte(aw)
+	_, err := o.encodeXDR(xw)
+	return []byte(aw), err
 }
 
 func (o IndexMessage) encodeXDR(xw *xdr.Writer) (int, error) {
-	if len(o.Folder) > 64 {
-		return xw.Tot(), xdr.ErrElementSizeExceeded
+	if l := len(o.Folder); l > 64 {
+		return xw.Tot(), xdr.ElementSizeExceeded("Folder", l, 64)
 	}
 	xw.WriteString(o.Folder)
 	xw.WriteUint32(uint32(len(o.Files)))
@@ -142,20 +150,28 @@ func (o FileInfo) EncodeXDR(w io.Writer) (int, error) {
 	return o.encodeXDR(xw)
 }
 
-func (o FileInfo) MarshalXDR() []byte {
+func (o FileInfo) MarshalXDR() ([]byte, error) {
 	return o.AppendXDR(make([]byte, 0, 128))
 }
 
-func (o FileInfo) AppendXDR(bs []byte) []byte {
+func (o FileInfo) MustMarshalXDR() []byte {
+	bs, err := o.MarshalXDR()
+	if err != nil {
+		panic(err)
+	}
+	return bs
+}
+
+func (o FileInfo) AppendXDR(bs []byte) ([]byte, error) {
 	var aw = xdr.AppendWriter(bs)
 	var xw = xdr.NewWriter(&aw)
-	o.encodeXDR(xw)
-	return []byte(aw)
+	_, err := o.encodeXDR(xw)
+	return []byte(aw), err
 }
 
 func (o FileInfo) encodeXDR(xw *xdr.Writer) (int, error) {
-	if len(o.Name) > 8192 {
-		return xw.Tot(), xdr.ErrElementSizeExceeded
+	if l := len(o.Name); l > 8192 {
+		return xw.Tot(), xdr.ElementSizeExceeded("Name", l, 8192)
 	}
 	xw.WriteString(o.Name)
 	xw.WriteUint32(o.Flags)
@@ -244,20 +260,28 @@ func (o FileInfoTruncated) EncodeXDR(w io.Writer) (int, error) {
 	return o.encodeXDR(xw)
 }
 
-func (o FileInfoTruncated) MarshalXDR() []byte {
+func (o FileInfoTruncated) MarshalXDR() ([]byte, error) {
 	return o.AppendXDR(make([]byte, 0, 128))
 }
 
-func (o FileInfoTruncated) AppendXDR(bs []byte) []byte {
+func (o FileInfoTruncated) MustMarshalXDR() []byte {
+	bs, err := o.MarshalXDR()
+	if err != nil {
+		panic(err)
+	}
+	return bs
+}
+
+func (o FileInfoTruncated) AppendXDR(bs []byte) ([]byte, error) {
 	var aw = xdr.AppendWriter(bs)
 	var xw = xdr.NewWriter(&aw)
-	o.encodeXDR(xw)
-	return []byte(aw)
+	_, err := o.encodeXDR(xw)
+	return []byte(aw), err
 }
 
 func (o FileInfoTruncated) encodeXDR(xw *xdr.Writer) (int, error) {
-	if len(o.Name) > 8192 {
-		return xw.Tot(), xdr.ErrElementSizeExceeded
+	if l := len(o.Name); l > 8192 {
+		return xw.Tot(), xdr.ElementSizeExceeded("Name", l, 8192)
 	}
 	xw.WriteString(o.Name)
 	xw.WriteUint32(o.Flags)
@@ -318,21 +342,29 @@ func (o BlockInfo) EncodeXDR(w io.Writer) (int, error) {
 	return o.encodeXDR(xw)
 }
 
-func (o BlockInfo) MarshalXDR() []byte {
+func (o BlockInfo) MarshalXDR() ([]byte, error) {
 	return o.AppendXDR(make([]byte, 0, 128))
 }
 
-func (o BlockInfo) AppendXDR(bs []byte) []byte {
+func (o BlockInfo) MustMarshalXDR() []byte {
+	bs, err := o.MarshalXDR()
+	if err != nil {
+		panic(err)
+	}
+	return bs
+}
+
+func (o BlockInfo) AppendXDR(bs []byte) ([]byte, error) {
 	var aw = xdr.AppendWriter(bs)
 	var xw = xdr.NewWriter(&aw)
-	o.encodeXDR(xw)
-	return []byte(aw)
+	_, err := o.encodeXDR(xw)
+	return []byte(aw), err
 }
 
 func (o BlockInfo) encodeXDR(xw *xdr.Writer) (int, error) {
 	xw.WriteUint32(o.Size)
-	if len(o.Hash) > 64 {
-		return xw.Tot(), xdr.ErrElementSizeExceeded
+	if l := len(o.Hash); l > 64 {
+		return xw.Tot(), xdr.ElementSizeExceeded("Hash", l, 64)
 	}
 	xw.WriteBytes(o.Hash)
 	return xw.Tot(), xw.Error()
@@ -396,24 +428,32 @@ func (o RequestMessage) EncodeXDR(w io.Writer) (int, error) {
 	return o.encodeXDR(xw)
 }
 
-func (o RequestMessage) MarshalXDR() []byte {
+func (o RequestMessage) MarshalXDR() ([]byte, error) {
 	return o.AppendXDR(make([]byte, 0, 128))
 }
 
-func (o RequestMessage) AppendXDR(bs []byte) []byte {
+func (o RequestMessage) MustMarshalXDR() []byte {
+	bs, err := o.MarshalXDR()
+	if err != nil {
+		panic(err)
+	}
+	return bs
+}
+
+func (o RequestMessage) AppendXDR(bs []byte) ([]byte, error) {
 	var aw = xdr.AppendWriter(bs)
 	var xw = xdr.NewWriter(&aw)
-	o.encodeXDR(xw)
-	return []byte(aw)
+	_, err := o.encodeXDR(xw)
+	return []byte(aw), err
 }
 
 func (o RequestMessage) encodeXDR(xw *xdr.Writer) (int, error) {
-	if len(o.Folder) > 64 {
-		return xw.Tot(), xdr.ErrElementSizeExceeded
+	if l := len(o.Folder); l > 64 {
+		return xw.Tot(), xdr.ElementSizeExceeded("Folder", l, 64)
 	}
 	xw.WriteString(o.Folder)
-	if len(o.Name) > 8192 {
-		return xw.Tot(), xdr.ErrElementSizeExceeded
+	if l := len(o.Name); l > 8192 {
+		return xw.Tot(), xdr.ElementSizeExceeded("Name", l, 8192)
 	}
 	xw.WriteString(o.Name)
 	xw.WriteUint64(o.Offset)
@@ -466,15 +506,23 @@ func (o ResponseMessage) EncodeXDR(w io.Writer) (int, error) {
 	return o.encodeXDR(xw)
 }
 
-func (o ResponseMessage) MarshalXDR() []byte {
+func (o ResponseMessage) MarshalXDR() ([]byte, error) {
 	return o.AppendXDR(make([]byte, 0, 128))
 }
 
-func (o ResponseMessage) AppendXDR(bs []byte) []byte {
+func (o ResponseMessage) MustMarshalXDR() []byte {
+	bs, err := o.MarshalXDR()
+	if err != nil {
+		panic(err)
+	}
+	return bs
+}
+
+func (o ResponseMessage) AppendXDR(bs []byte) ([]byte, error) {
 	var aw = xdr.AppendWriter(bs)
 	var xw = xdr.NewWriter(&aw)
-	o.encodeXDR(xw)
-	return []byte(aw)
+	_, err := o.encodeXDR(xw)
+	return []byte(aw), err
 }
 
 func (o ResponseMessage) encodeXDR(xw *xdr.Writer) (int, error) {
@@ -545,28 +593,36 @@ func (o ClusterConfigMessage) EncodeXDR(w io.Writer) (int, error) {
 	return o.encodeXDR(xw)
 }
 
-func (o ClusterConfigMessage) MarshalXDR() []byte {
+func (o ClusterConfigMessage) MarshalXDR() ([]byte, error) {
 	return o.AppendXDR(make([]byte, 0, 128))
 }
 
-func (o ClusterConfigMessage) AppendXDR(bs []byte) []byte {
+func (o ClusterConfigMessage) MustMarshalXDR() []byte {
+	bs, err := o.MarshalXDR()
+	if err != nil {
+		panic(err)
+	}
+	return bs
+}
+
+func (o ClusterConfigMessage) AppendXDR(bs []byte) ([]byte, error) {
 	var aw = xdr.AppendWriter(bs)
 	var xw = xdr.NewWriter(&aw)
-	o.encodeXDR(xw)
-	return []byte(aw)
+	_, err := o.encodeXDR(xw)
+	return []byte(aw), err
 }
 
 func (o ClusterConfigMessage) encodeXDR(xw *xdr.Writer) (int, error) {
-	if len(o.ClientName) > 64 {
-		return xw.Tot(), xdr.ErrElementSizeExceeded
+	if l := len(o.ClientName); l > 64 {
+		return xw.Tot(), xdr.ElementSizeExceeded("ClientName", l, 64)
 	}
 	xw.WriteString(o.ClientName)
-	if len(o.ClientVersion) > 64 {
-		return xw.Tot(), xdr.ErrElementSizeExceeded
+	if l := len(o.ClientVersion); l > 64 {
+		return xw.Tot(), xdr.ElementSizeExceeded("ClientVersion", l, 64)
 	}
 	xw.WriteString(o.ClientVersion)
-	if len(o.Folders) > 64 {
-		return xw.Tot(), xdr.ErrElementSizeExceeded
+	if l := len(o.Folders); l > 64 {
+		return xw.Tot(), xdr.ElementSizeExceeded("Folders", l, 64)
 	}
 	xw.WriteUint32(uint32(len(o.Folders)))
 	for i := range o.Folders {
@@ -575,8 +631,8 @@ func (o ClusterConfigMessage) encodeXDR(xw *xdr.Writer) (int, error) {
 			return xw.Tot(), err
 		}
 	}
-	if len(o.Options) > 64 {
-		return xw.Tot(), xdr.ErrElementSizeExceeded
+	if l := len(o.Options); l > 64 {
+		return xw.Tot(), xdr.ElementSizeExceeded("Options", l, 64)
 	}
 	xw.WriteUint32(uint32(len(o.Options)))
 	for i := range o.Options {
@@ -604,7 +660,7 @@ func (o *ClusterConfigMessage) decodeXDR(xr *xdr.Reader) error {
 	o.ClientVersion = xr.ReadStringMax(64)
 	_FoldersSize := int(xr.ReadUint32())
 	if _FoldersSize > 64 {
-		return xdr.ErrElementSizeExceeded
+		return xdr.ElementSizeExceeded("Folders", _FoldersSize, 64)
 	}
 	o.Folders = make([]Folder, _FoldersSize)
 	for i := range o.Folders {
@@ -612,7 +668,7 @@ func (o *ClusterConfigMessage) decodeXDR(xr *xdr.Reader) error {
 	}
 	_OptionsSize := int(xr.ReadUint32())
 	if _OptionsSize > 64 {
-		return xdr.ErrElementSizeExceeded
+		return xdr.ElementSizeExceeded("Options", _OptionsSize, 64)
 	}
 	o.Options = make([]Option, _OptionsSize)
 	for i := range o.Options {
@@ -654,20 +710,28 @@ func (o Folder) EncodeXDR(w io.Writer) (int, error) {
 	return o.encodeXDR(xw)
 }
 
-func (o Folder) MarshalXDR() []byte {
+func (o Folder) MarshalXDR() ([]byte, error) {
 	return o.AppendXDR(make([]byte, 0, 128))
 }
 
-func (o Folder) AppendXDR(bs []byte) []byte {
+func (o Folder) MustMarshalXDR() []byte {
+	bs, err := o.MarshalXDR()
+	if err != nil {
+		panic(err)
+	}
+	return bs
+}
+
+func (o Folder) AppendXDR(bs []byte) ([]byte, error) {
 	var aw = xdr.AppendWriter(bs)
 	var xw = xdr.NewWriter(&aw)
-	o.encodeXDR(xw)
-	return []byte(aw)
+	_, err := o.encodeXDR(xw)
+	return []byte(aw), err
 }
 
 func (o Folder) encodeXDR(xw *xdr.Writer) (int, error) {
-	if len(o.ID) > 64 {
-		return xw.Tot(), xdr.ErrElementSizeExceeded
+	if l := len(o.ID); l > 64 {
+		return xw.Tot(), xdr.ElementSizeExceeded("ID", l, 64)
 	}
 	xw.WriteString(o.ID)
 	xw.WriteUint32(uint32(len(o.Devices)))
@@ -735,20 +799,28 @@ func (o Device) EncodeXDR(w io.Writer) (int, error) {
 	return o.encodeXDR(xw)
 }
 
-func (o Device) MarshalXDR() []byte {
+func (o Device) MarshalXDR() ([]byte, error) {
 	return o.AppendXDR(make([]byte, 0, 128))
 }
 
-func (o Device) AppendXDR(bs []byte) []byte {
+func (o Device) MustMarshalXDR() []byte {
+	bs, err := o.MarshalXDR()
+	if err != nil {
+		panic(err)
+	}
+	return bs
+}
+
+func (o Device) AppendXDR(bs []byte) ([]byte, error) {
 	var aw = xdr.AppendWriter(bs)
 	var xw = xdr.NewWriter(&aw)
-	o.encodeXDR(xw)
-	return []byte(aw)
+	_, err := o.encodeXDR(xw)
+	return []byte(aw), err
 }
 
 func (o Device) encodeXDR(xw *xdr.Writer) (int, error) {
-	if len(o.ID) > 32 {
-		return xw.Tot(), xdr.ErrElementSizeExceeded
+	if l := len(o.ID); l > 32 {
+		return xw.Tot(), xdr.ElementSizeExceeded("ID", l, 32)
 	}
 	xw.WriteBytes(o.ID)
 	xw.WriteUint32(o.Flags)
@@ -807,24 +879,32 @@ func (o Option) EncodeXDR(w io.Writer) (int, error) {
 	return o.encodeXDR(xw)
 }
 
-func (o Option) MarshalXDR() []byte {
+func (o Option) MarshalXDR() ([]byte, error) {
 	return o.AppendXDR(make([]byte, 0, 128))
 }
 
-func (o Option) AppendXDR(bs []byte) []byte {
+func (o Option) MustMarshalXDR() []byte {
+	bs, err := o.MarshalXDR()
+	if err != nil {
+		panic(err)
+	}
+	return bs
+}
+
+func (o Option) AppendXDR(bs []byte) ([]byte, error) {
 	var aw = xdr.AppendWriter(bs)
 	var xw = xdr.NewWriter(&aw)
-	o.encodeXDR(xw)
-	return []byte(aw)
+	_, err := o.encodeXDR(xw)
+	return []byte(aw), err
 }
 
 func (o Option) encodeXDR(xw *xdr.Writer) (int, error) {
-	if len(o.Key) > 64 {
-		return xw.Tot(), xdr.ErrElementSizeExceeded
+	if l := len(o.Key); l > 64 {
+		return xw.Tot(), xdr.ElementSizeExceeded("Key", l, 64)
 	}
 	xw.WriteString(o.Key)
-	if len(o.Value) > 1024 {
-		return xw.Tot(), xdr.ErrElementSizeExceeded
+	if l := len(o.Value); l > 1024 {
+		return xw.Tot(), xdr.ElementSizeExceeded("Value", l, 1024)
 	}
 	xw.WriteString(o.Value)
 	return xw.Tot(), xw.Error()
@@ -873,20 +953,28 @@ func (o CloseMessage) EncodeXDR(w io.Writer) (int, error) {
 	return o.encodeXDR(xw)
 }
 
-func (o CloseMessage) MarshalXDR() []byte {
+func (o CloseMessage) MarshalXDR() ([]byte, error) {
 	return o.AppendXDR(make([]byte, 0, 128))
 }
 
-func (o CloseMessage) AppendXDR(bs []byte) []byte {
+func (o CloseMessage) MustMarshalXDR() []byte {
+	bs, err := o.MarshalXDR()
+	if err != nil {
+		panic(err)
+	}
+	return bs
+}
+
+func (o CloseMessage) AppendXDR(bs []byte) ([]byte, error) {
 	var aw = xdr.AppendWriter(bs)
 	var xw = xdr.NewWriter(&aw)
-	o.encodeXDR(xw)
-	return []byte(aw)
+	_, err := o.encodeXDR(xw)
+	return []byte(aw), err
 }
 
 func (o CloseMessage) encodeXDR(xw *xdr.Writer) (int, error) {
-	if len(o.Reason) > 1024 {
-		return xw.Tot(), xdr.ErrElementSizeExceeded
+	if l := len(o.Reason); l > 1024 {
+		return xw.Tot(), xdr.ElementSizeExceeded("Reason", l, 1024)
 	}
 	xw.WriteString(o.Reason)
 	return xw.Tot(), xw.Error()
@@ -927,15 +1015,23 @@ func (o EmptyMessage) EncodeXDR(w io.Writer) (int, error) {
 	return o.encodeXDR(xw)
 }
 
-func (o EmptyMessage) MarshalXDR() []byte {
+func (o EmptyMessage) MarshalXDR() ([]byte, error) {
 	return o.AppendXDR(make([]byte, 0, 128))
 }
 
-func (o EmptyMessage) AppendXDR(bs []byte) []byte {
+func (o EmptyMessage) MustMarshalXDR() []byte {
+	bs, err := o.MarshalXDR()
+	if err != nil {
+		panic(err)
+	}
+	return bs
+}
+
+func (o EmptyMessage) AppendXDR(bs []byte) ([]byte, error) {
 	var aw = xdr.AppendWriter(bs)
 	var xw = xdr.NewWriter(&aw)
-	o.encodeXDR(xw)
-	return []byte(aw)
+	_, err := o.encodeXDR(xw)
+	return []byte(aw), err
 }
 
 func (o EmptyMessage) encodeXDR(xw *xdr.Writer) (int, error) {
diff --git a/protocol.go b/protocol.go
index 19cdfbb16..08ef226f0 100644
--- a/protocol.go
+++ b/protocol.go
@@ -126,7 +126,7 @@ type hdrMsg struct {
 }
 
 type encodable interface {
-	AppendXDR([]byte) []byte
+	AppendXDR([]byte) ([]byte, error)
 }
 
 const (
@@ -483,7 +483,11 @@ func (c *rawConnection) writerLoop() {
 		case hm := <-c.outbox:
 			if hm.msg != nil {
 				// Uncompressed message in uncBuf
-				uncBuf = hm.msg.AppendXDR(uncBuf[:0])
+				uncBuf, err = hm.msg.AppendXDR(uncBuf[:0])
+				if err != nil {
+					c.close(err)
+					return
+				}
 
 				if len(uncBuf) >= c.compressionThreshold {
 					// Use compression for large messages
diff --git a/protocol_test.go b/protocol_test.go
index cc6f9472a..a7bb1416c 100644
--- a/protocol_test.go
+++ b/protocol_test.go
@@ -25,6 +25,7 @@ import (
 	"io/ioutil"
 	"os"
 	"reflect"
+	"strings"
 	"testing"
 	"testing/quick"
 
@@ -369,7 +370,7 @@ func testMarshal(t *testing.T, prefix string, m1, m2 message) bool {
 	}
 
 	_, err := m1.EncodeXDR(&buf)
-	if err == xdr.ErrElementSizeExceeded {
+	if err != nil && strings.Contains(err.Error(), "exceeds size") {
 		return true
 	}
 	if err != nil {