diff --git a/noise-helpers.go b/noise-helpers.go
index 1b2746c..af11f09 100644
--- a/noise-helpers.go
+++ b/noise-helpers.go
@@ -78,12 +78,14 @@ func setZero(arr []byte) {
 	}
 }
 
-func newPrivateKey() (sk NoisePrivateKey, err error) {
-	// clamping: https://cr.yp.to/ecdh.html
-	_, err = rand.Read(sk[:])
+func (sk *NoisePrivateKey) clamp() {
 	sk[0] &= 248
-	sk[31] &= 127
-	sk[31] |= 64
+	sk[31] = (sk[31] & 127) | 64
+}
+
+func newPrivateKey() (sk NoisePrivateKey, err error) {
+	_, err = rand.Read(sk[:])
+	sk.clamp()
 	return
 }
 
diff --git a/noise-types.go b/noise-types.go
index df6ee77..902905e 100644
--- a/noise-types.go
+++ b/noise-types.go
@@ -45,8 +45,10 @@ func (key NoisePrivateKey) Equals(tar NoisePrivateKey) bool {
 	return subtle.ConstantTimeCompare(key[:], tar[:]) == 1
 }
 
-func (key *NoisePrivateKey) FromHex(src string) error {
-	return loadExactHex(key[:], src)
+func (key *NoisePrivateKey) FromHex(src string) (err error) {
+	err = loadExactHex(key[:], src)
+	key.clamp()
+	return
 }
 
 func (key NoisePrivateKey) ToHex() string {