VERSION                 |  2 +-
 cmd/streebog256/main.go |  4 +++-
 cmd/streebog512/main.go |  4 +++-
 gost3410/vko2001.go     |  4 +++-
 gost3410/vko2012.go     |  8 ++++++--
 gost34112012256/kdf.go  | 24 ++++++++++++++++++------
 install.texi            |  2 +-
 news.texi               |  4 ++++
 prfplus/gost.go         |  4 +++-

diff --git a/VERSION b/VERSION
index 89035672d7aef304f3b141b9a0627f749d50ddb0acfdc9dd84f2de6aeeabf4ec..fee4582f77aca97abcf501894498f5dbd35aa8a7e54fcd4e8f11b78debfe3cc5 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-4.2.2
+4.2.3
diff --git a/cmd/streebog256/main.go b/cmd/streebog256/main.go
index 5fc2c972f06413be4904c2da53a4a4cdff6366dd27966ae021e48d507d3a6209..e4eb52c6798b3747dfe58fc851c755d712da19dd1ae74aab705949512bbd9519 100644
--- a/cmd/streebog256/main.go
+++ b/cmd/streebog256/main.go
@@ -38,6 +38,8 @@ 		fmt.Println(gogost.Version)
 		return
 	}
 	h := gost34112012256.New()
-	io.Copy(h, os.Stdin)
+	if _, err := io.Copy(h, os.Stdin); err != nil {
+		panic(err)
+	}
 	fmt.Println(hex.EncodeToString(h.Sum(nil)))
 }
diff --git a/cmd/streebog512/main.go b/cmd/streebog512/main.go
index 4d1a319baacc8a431444de2bd9a792718f2a7eec1dd4fff6fcb4ef0d75e9e864..4cf048f35da31b07a11dda77c9fa3816170c1166bb31d4eeb2bf514d80a23f2a 100644
--- a/cmd/streebog512/main.go
+++ b/cmd/streebog512/main.go
@@ -38,6 +38,8 @@ 		fmt.Println(gogost.Version)
 		return
 	}
 	h := gost34112012512.New()
-	io.Copy(h, os.Stdin)
+	if _, err := io.Copy(h, os.Stdin); err != nil {
+		panic(err)
+	}
 	fmt.Println(hex.EncodeToString(h.Sum(nil)))
 }
diff --git a/gost3410/vko2001.go b/gost3410/vko2001.go
index 6cf72d9e67032ac8c36738e7c47fe1e9cc53c83785fb7595ad571bc66aa98770..5ffe784e341a5b50246457b01dc6929900cb10d35457fcb0f9fe17f64269f226 100644
--- a/gost3410/vko2001.go
+++ b/gost3410/vko2001.go
@@ -34,6 +34,8 @@ 	if err != nil {
 		return nil, err
 	}
 	h := gost341194.New(&gost28147.SboxIdGostR341194CryptoProParamSet)
-	h.Write(key)
+	if _, err = h.Write(key); err != nil {
+		return nil, err
+	}
 	return h.Sum(key[:0]), nil
 }
diff --git a/gost3410/vko2012.go b/gost3410/vko2012.go
index bfd0b9c1f93c8e2421e4f242551a730a1b37d29afd8f0298fac2a64b35be9655..d78e5a59d8f5d84f0cac7181f42bcfdbb335c4e8abfad4c5b8e0a8f36b6f1a16 100644
--- a/gost3410/vko2012.go
+++ b/gost3410/vko2012.go
@@ -30,7 +30,9 @@ 	if err != nil {
 		return nil, err
 	}
 	h := gost34112012256.New()
-	h.Write(key)
+	if _, err = h.Write(key); err != nil {
+		return nil, err
+	}
 	return h.Sum(key[:0]), nil
 }
 
@@ -42,6 +44,8 @@ 	if err != nil {
 		return nil, err
 	}
 	h := gost34112012512.New()
-	h.Write(key)
+	if _, err = h.Write(key); err != nil {
+		return nil, err
+	}
 	return h.Sum(key[:0]), nil
 }
diff --git a/gost34112012256/kdf.go b/gost34112012256/kdf.go
index baa15e3629b48d286e972cf198aa0425abcaa82d25eec1c297b47b5b1a15be50..5ffbc27cd80ad19c207504c6e4f9dc145d512ab7f7e00d60172109f42817c380 100644
--- a/gost34112012256/kdf.go
+++ b/gost34112012256/kdf.go
@@ -29,12 +29,24 @@ 	return &KDF{hmac.New(New, key)}
 }
 
 func (kdf *KDF) Derive(dst, label, seed []byte) (r []byte) {
-	kdf.h.Write([]byte{0x01})
-	kdf.h.Write(label)
-	kdf.h.Write([]byte{0x00})
-	kdf.h.Write(seed)
-	kdf.h.Write([]byte{0x01})
-	kdf.h.Write([]byte{0x00})
+	if _, err := kdf.h.Write([]byte{0x01}); err != nil {
+		panic(err)
+	}
+	if _, err := kdf.h.Write(label); err != nil {
+		panic(err)
+	}
+	if _, err := kdf.h.Write([]byte{0x00}); err != nil {
+		panic(err)
+	}
+	if _, err := kdf.h.Write(seed); err != nil {
+		panic(err)
+	}
+	if _, err := kdf.h.Write([]byte{0x01}); err != nil {
+		panic(err)
+	}
+	if _, err := kdf.h.Write([]byte{0x00}); err != nil {
+		panic(err)
+	}
 	r = kdf.h.Sum(dst)
 	kdf.h.Reset()
 	return r
diff --git a/install.texi b/install.texi
index ea88b485fbdcbe0d4b643ce2a25129e59389a69e8edb9587b419d9c07313d19b..bf2e088d980e989dd3d65385b25d660a752c8a901e9f39eb1a6daaf362e13b86 100644
--- a/install.texi
+++ b/install.texi
@@ -1,7 +1,7 @@
 @node Download
 @unnumbered Download
 
-@set VERSION 4.2.2
+@set VERSION 4.2.3
 
 Preferable way is to download tarball with the signature from
 website and, for example, run tests with benchmarks:
diff --git a/news.texi b/news.texi
index 67c5fba7032990fea0a74d0fb72c5a83e483455dd9210281f2421f8bf8158179..7e4b13cbe684ae2c8415719dcfbb2ad84b885014dc1bdf4080aeabec968e90f7 100644
--- a/news.texi
+++ b/news.texi
@@ -3,6 +3,10 @@ @unnumbered News
 
 @table @strong
 
+@anchor{Release 4.2.3}
+@item 4.2.3
+    Panic on all possible hash @code{Write} errors.
+
 @anchor{Release 4.2.2}
 @item 4.2.2
     More 34.10-2012 test vectors.
diff --git a/prfplus/gost.go b/prfplus/gost.go
index e6d51dbd46da5b56c3422a03fdd6341cbafc57bf2a9940ab4ede6e2452f7eb99..e671f494d82c4b9fe4f26315c66c9bfef39844a408faf5c4d8916f3399ea688b 100644
--- a/prfplus/gost.go
+++ b/prfplus/gost.go
@@ -39,7 +39,9 @@ 	return prf.h.Size()
 }
 
 func (prf PRFIPsecPRFPlusGOSTR34112012) Derive(salt []byte) []byte {
-	prf.h.Write(salt)
+	if _, err := prf.h.Write(salt); err != nil {
+		panic(err)
+	}
 	sum := prf.h.Sum(nil)
 	prf.h.Reset()
 	return sum