diff --git a/hpke/hybridkem.go b/hpke/hybridkem.go
index 29155520..2abffefd 100644
--- a/hpke/hybridkem.go
+++ b/hpke/hybridkem.go
@@ -165,7 +165,7 @@ func (h hybridKEM) DeriveKeyPair(seed []byte) (kem.PublicKey, kem.PrivateKey) {
 	}
 
 	outputSeedSize := h.kemA.SeedSize() + h.kemB.SeedSize()
-	dkpPrk := h.labeledExtract(nil, []byte("dkp_prk"), seed)
+	dkpPrk := h.labeledExtract([]byte(""), []byte("dkp_prk"), seed)
 	bytes := h.labeledExpand(
 		dkpPrk,
 		[]byte("sk"),
diff --git a/hpke/kembase.go b/hpke/kembase.go
index c68f6da0..a15765f6 100644
--- a/hpke/kembase.go
+++ b/hpke/kembase.go
@@ -40,7 +40,7 @@ func (k kemBase) getSuiteID() (sid [5]byte) {
 }
 
 func (k kemBase) extractExpand(dh, kemCtx []byte) []byte {
-	eaePkr := k.labeledExtract(nil, []byte("eae_prk"), dh)
+	eaePkr := k.labeledExtract([]byte(""), []byte("eae_prk"), dh)
 	return k.labeledExpand(
 		eaePkr,
 		[]byte("shared_secret"),
@@ -49,7 +49,6 @@ func (k kemBase) extractExpand(dh, kemCtx []byte) []byte {
 	)
 }
 
-// nolint:unparam
 func (k kemBase) labeledExtract(salt, label, info []byte) []byte {
 	suiteID := k.getSuiteID()
 	labeledIKM := append(append(append(append(
diff --git a/hpke/shortkem.go b/hpke/shortkem.go
index 6b5491f6..ca0b8843 100644
--- a/hpke/shortkem.go
+++ b/hpke/shortkem.go
@@ -53,7 +53,7 @@ func (s shortKEM) DeriveKeyPair(seed []byte) (kem.PublicKey, kem.PrivateKey) {
 		bitmask = 0x01
 	}
 
-	dkpPrk := s.labeledExtract(nil, []byte("dkp_prk"), seed)
+	dkpPrk := s.labeledExtract([]byte(""), []byte("dkp_prk"), seed)
 	var bytes []byte
 	ctr := 0
 	for skBig := new(big.Int); skBig.Sign() == 0 || skBig.Cmp(s.Params().N) >= 0; ctr++ {
diff --git a/hpke/xkem.go b/hpke/xkem.go
index 9a811f95..58ca2bee 100644
--- a/hpke/xkem.go
+++ b/hpke/xkem.go
@@ -59,7 +59,7 @@ func (x xKEM) DeriveKeyPair(seed []byte) (kem.PublicKey, kem.PrivateKey) {
 		panic(kem.ErrSeedSize)
 	}
 	sk := &xKEMPrivKey{scheme: x, priv: make([]byte, x.size)}
-	dkpPrk := x.labeledExtract(nil, []byte("dkp_prk"), seed)
+	dkpPrk := x.labeledExtract([]byte(""), []byte("dkp_prk"), seed)
 	bytes := x.labeledExpand(
 		dkpPrk,
 		[]byte("sk"),