go.mod                        | 2 +-
 internal/gost34112012/hash.go | 2 +-
 mgm/mode.go                   | 8 ++------
 mgm/mul64.go                  | 4 +---

diff --git a/go.mod b/go.mod
index 093e0945fa0d5cf4dd7b18524408bafd05710f77c41c9dd4e29fa948f4ca9b21..f892ca64f132883bbf1c2c4534f3a3835907956e831eb3400ff99e59c909b811 100644
--- a/go.mod
+++ b/go.mod
@@ -1,5 +1,5 @@
 module go.cypherpunks.ru/gogost/v5
 
-go 1.20
+go 1.21
 
 require golang.org/x/crypto v0.16.0
diff --git a/internal/gost34112012/hash.go b/internal/gost34112012/hash.go
index b17397f38408986b2f5bcd61289dc3fa11614974e44bfb07d36d7984a03c6697..344784564ce6e9cbe62a81cc9ed790a7d04031b488219f4da324193a815f71d3 100644
--- a/internal/gost34112012/hash.go
+++ b/internal/gost34112012/hash.go
@@ -264,8 +264,8 @@
 func (h *Hash) Reset() {
 	h.n = 0
 	h.buf = nil
+	clear(h.chk)
 	for i := 0; i < BlockSize; i++ {
-		h.chk[i] = 0
 		if h.size == 32 {
 			h.hsh[i] = 1
 		} else {
diff --git a/mgm/mode.go b/mgm/mode.go
index 566a2a3918648f81d969bd3fe16847581a4f740739e55ba511c2070eb3e554d6..6c01ca3d00c929d8dff1501e74088a96b5cecbf3fb939e99101e25fa62f41081 100644
--- a/mgm/mode.go
+++ b/mgm/mode.go
@@ -110,9 +110,7 @@ 	}
 }
 
 func (mgm *MGM) auth(out, text, ad []byte) {
-	for i := 0; i < mgm.BlockSize; i++ {
-		mgm.sum[i] = 0
-	}
+	clear(mgm.sum)
 	adLen := len(ad) * 8
 	textLen := len(text) * 8
 	mgm.icn[0] |= 0x80
@@ -129,9 +127,7 @@ 		ad = ad[mgm.BlockSize:]
 	}
 	if len(ad) > 0 {
 		copy(mgm.padded, ad)
-		for i := len(ad); i < mgm.BlockSize; i++ {
-			mgm.padded[i] = 0
-		}
+		clear(mgm.padded[len(ad):])
 		mgm.cipher.Encrypt(mgm.bufC, mgm.bufP)
 		subtle.XORBytes(mgm.sum, mgm.sum, mgm.mul.Mul(mgm.bufC, mgm.padded))
 		incr(mgm.bufP[:mgm.BlockSize/2])
diff --git a/mgm/mul64.go b/mgm/mul64.go
index 0ef063a7f405bd6399d0a25c9e2aaddcf16182dd2aeb1524fe2a5154adbe9178..ebe3891f20e2aacc7c4f8e5fb682441ee6c5d06e5a674e06bcad06e0b81514ed 100644
--- a/mgm/mul64.go
+++ b/mgm/mul64.go
@@ -57,9 +57,7 @@ 		mul.y.Rsh(mul.y, 1)
 	}
 	zBytes := mul.z.Bytes()
 	rem := len(x) - len(zBytes)
-	for i := 0; i < rem; i++ {
-		mul.buf[i] = 0
-	}
+	clear(mul.buf[:rem])
 	copy(mul.buf[rem:], zBytes)
 	return mul.buf[:]
 }