diff --git a/http.go b/http.go
index 047054f..d0098e7 100644
--- a/http.go
+++ b/http.go
@@ -83,6 +83,7 @@ type transport struct {
 
 func (t *transport) RoundTrip(req *http.Request) (*http.Response, error) {
 	if t.sign {
+		req = req.Clone(req.Context())
 		// Signing does not read or close the body
 		err := t.signer.Sign(req)
 		if err != nil {
diff --git a/keyutil/jwk.go b/keyutil/jwk.go
index e77e256..092215d 100644
--- a/keyutil/jwk.go
+++ b/keyutil/jwk.go
@@ -208,11 +208,11 @@ func (ec *jwkEC) PublicKey() (*ecdsa.PublicKey, error) {
 		return nil, err
 	}
 
-	if len(ec.X.Bytes()) != byteLen {
-		return nil, fmt.Errorf("X coordinate must be %d byte length for curve '%s'. Got '%d'", byteLen, ec.Curve, len(ec.X.Bytes()))
+	if ec.X.BitLen() > byteLen*8 {
+		return nil, fmt.Errorf("X coordinate exceeds %d bytes for curve '%s'", byteLen, ec.Curve)
 	}
-	if len(ec.Y.Bytes()) != byteLen {
-		return nil, fmt.Errorf("Y coordinate must be %d byte length for curve '%s'. Got '%d'", byteLen, ec.Curve, len(ec.Y.Bytes()))
+	if ec.Y.BitLen() > byteLen*8 {
+		return nil, fmt.Errorf("Y coordinate exceeds %d bytes for curve '%s'", byteLen, ec.Curve)
 	}
 
 	return &ecdsa.PublicKey{
@@ -249,8 +249,8 @@ func (ec *jwkEC) PrivateKey() (*ecdsa.PrivateKey, error) {
 		return nil, err
 	}
 
-	if len(ec.D.Bytes()) != byteLen {
-		return nil, fmt.Errorf("D coordinate must be %d byte length for curve '%s'. Got '%d'", byteLen, ec.Curve, len(ec.D.Bytes()))
+	if ec.D.BitLen() > byteLen*8 {
+		return nil, fmt.Errorf("D coordinate exceeds %d bytes for curve '%s'", byteLen, ec.Curve)
 	}
 
 	return &ecdsa.PrivateKey{