diff --git a/argon2i.go b/argon2i.go
index 937d257..c948b28 100644
--- a/argon2i.go
+++ b/argon2i.go
@@ -35,14 +35,13 @@ const (
 	argon2iDefaultMemory   = 32 * 1024
 	argon2iDefaultTime     = 4
 	argon2iDefaultThreads  = 4
-	argon2iKeySize         = 32
+	argon2iDefaultKeySize  = 32
 	argon2iDefaultSaltSize = 16
-	argon2iMaxSaltSize     = 16 // 0xFFFFFFFF
 )
 
 // Argon2iSettings returns argon2i settings with the provided parameter.
-func Argon2iSettings(m, t, p int, salts ...string) (string, error) {
-	settings := fmt.Sprintf("%sv=19$m=%d,t=%d,p=%d", Argon2iPrefix, m, t, p)
+func Argon2iSettings(m, t, p, k int, salts ...string) (string, error) {
+	settings := fmt.Sprintf("%sv=19$m=%d,t=%d,p=%d,k=%d", Argon2iPrefix, m, t, p, k)
 	salt := strings.Join(salts, "")
 	if salt == "" {
 		b := make([]byte, argon2iDefaultSaltSize)
@@ -68,14 +67,12 @@ func argon2iAlgorithm(password, settings string) (string, error) {
 			return "", fmt.Errorf("base64 decode [%s]: %v", salt, err)
 		}
 	}
-	if len(saltBytes) > argon2iMaxSaltSize {
-		saltBytes = saltBytes[:argon2iMaxSaltSize]
-	}
 	memory := parameter.GetInt("m", argon2iDefaultMemory)
 	time := parameter.GetInt("t", argon2iDefaultTime)
 	threads := parameter.GetInt("p", argon2iDefaultThreads)
+	keySize := parameter.GetInt("k", argon2iDefaultKeySize)
 
-	hash := argon2.Key(passwordBytes, saltBytes, uint32(time), uint32(memory), uint8(threads), argon2iKeySize)
+	hash := argon2.Key(passwordBytes, saltBytes, uint32(time), uint32(memory), uint8(threads), uint32(keySize))
 
 	p := []string{}
 	if memory != argon2iDefaultMemory {
@@ -87,6 +84,9 @@ func argon2iAlgorithm(password, settings string) (string, error) {
 	if threads != argon2iDefaultThreads {
 		p = append(p, "p="+strconv.Itoa(threads))
 	}
+	if keySize != argon2iDefaultKeySize {
+		p = append(p, "k="+strconv.Itoa(keySize))
+	}
 
 	buf := bytes.Buffer{}
 	buf.Write([]byte(Argon2iPrefix))
diff --git a/argon2i_test.go b/argon2i_test.go
index 012bea5..f33e29c 100644
--- a/argon2i_test.go
+++ b/argon2i_test.go
@@ -33,22 +33,30 @@ func TestArgon2i(t *testing.T) {
 		}
 	}
 
-	t.Run(testFn("generate salt", "$argon2i$v=19$m=65536,t=2,p=4$", "$argon2i$v=19$m=65536,t=2$", nil))
-	t.Run(testFn("password", "$argon2i$v=19$m=65536,t=2,p=4$c29tZXNhbHQ", "$argon2i$v=19$m=65536,t=2$c29tZXNhbHQ$IMit9qkFULCMA/ViizL57cnTLOa5DiVM9eMwpAvPwr4", nil))
-	t.Run(testFn("another password", "$argon2i$v=19$m=65536,t=2,p=4$YW5vdGhlcnNhbHQ", "$argon2i$v=19$m=65536,t=2$YW5vdGhlcnNhbHQ$BCRltpeTFX0QYrELiOXWGZniID9nOUsBPy8Bu0SE7bM", nil))
-	t.Run(testFn("password", "$argon2i$v=19$m=65536,t=2,p=1$bG9uZ3NhbHRsb25nc2FsdGxvbmc", "$argon2i$v=19$m=65536,t=2,p=1$bG9uZ3NhbHRsb25nc2FsdA$8BZnxCqANQ3mGYITjgezarZ/b5vivfVRVy3cWwwXGHI", nil))
-	t.Run(testFn("ignore-hash-in-settings", "$argon2i$v=19$m=65536,t=2$bG9uZ3NhbHRsb25nc2FsdGxvbmc$rDmQABiNkSO3bGHbBUkShgb7wIlBP8HHfq6nDH+Sqss", "$argon2i$v=19$m=65536,t=2$bG9uZ3NhbHRsb25nc2FsdA$Cfa1JVLA/wGtR7UeWI+Q+ZOfMmyPchePKy2h+kjryG8", nil))
-	t.Run(testFn("password", "$argon2i$v=19$m=65536,t=3,p=1$bG9uZ3NhbHRsb25nc2FsdA", "$argon2i$v=19$m=65536,t=3,p=1$bG9uZ3NhbHRsb25nc2FsdA$K2rLfVoQG17LuUn26otasTX1WBXjr6hi5NZXKKxmYrs", nil))
+	t.Run(testFn("generate salt", "$argon2i$v=19$m=65536,t=2,p=4$",
+		"$argon2i$v=19$m=65536,t=2$", nil))
+	t.Run(testFn("password", "$argon2i$v=19$m=65536,t=2,p=4$c29tZXNhbHQ",
+		"$argon2i$v=19$m=65536,t=2$c29tZXNhbHQ$IMit9qkFULCMA/ViizL57cnTLOa5DiVM9eMwpAvPwr4", nil))
+	t.Run(testFn("another password", "$argon2i$v=19$m=65536,t=2,p=4$YW5vdGhlcnNhbHQ",
+		"$argon2i$v=19$m=65536,t=2$YW5vdGhlcnNhbHQ$BCRltpeTFX0QYrELiOXWGZniID9nOUsBPy8Bu0SE7bM", nil))
+	t.Run(testFn("password", "$argon2i$v=19$m=65536,t=2,p=1$bG9uZ3NhbHRsb25nc2FsdGxvbmc",
+		"$argon2i$v=19$m=65536,t=2,p=1$bG9uZ3NhbHRsb25nc2FsdGxvbmc$N2zfK+oCIRMbTX04zZS4X2uLKX3SK0KkNxyCw/NURrU", nil))
+	t.Run(testFn("ignore-hash-in-settings", "$argon2i$v=19$m=65536,t=2$bG9uZ3NhbHRsb25nc2FsdGxvbmc$rDmQABiNkSO3bGHbBUkShgb7wIlBP8HHfq6nDH+Sqss",
+		"$argon2i$v=19$m=65536,t=2$bG9uZ3NhbHRsb25nc2FsdGxvbmc$xY9IRFH+zQduVUYoZfSoT6tylET3/AUIOMS3rFF0x0o", nil))
+	t.Run(testFn("password", "$argon2i$v=19$m=65536,t=3,p=1$bG9uZ3NhbHRsb25nc2FsdA",
+		"$argon2i$v=19$m=65536,t=3,p=1$bG9uZ3NhbHRsb25nc2FsdA$K2rLfVoQG17LuUn26otasTX1WBXjr6hi5NZXKKxmYrs", nil))
+	t.Run(testFn("password", "$argon2i$v=19$m=65536,t=3,p=1,k=64$bG9uZ3NhbHRsb25nc2FsdA",
+		"$argon2i$v=19$m=65536,t=3,p=1,k=64$bG9uZ3NhbHRsb25nc2FsdA$7DnJ2B7gxZDMEk+HVNDpIuTtOxDkwDaA0IhvuiBn9oeBTXpqBPxP9iro2cPiFongTwoFHHpVrqiL8JvMXrb63Q", nil))
 }
 
 func TestArgon2iSettings(t *testing.T) {
-	testFn := func(m, t, p int, expectSettingsPrefix string) (string, func(*testing.T)) {
-		return fmt.Sprintf("m=%d,t=%d,p=%d", m, t, p), func(tt *testing.T) {
-			settings, err := crypt.Argon2iSettings(m, t, p)
+	testFn := func(m, t, p, k int, expectSettingsPrefix string) (string, func(*testing.T)) {
+		return fmt.Sprintf("m=%d,t=%d,p=%d,k=%d", m, t, p, k), func(tt *testing.T) {
+			settings, err := crypt.Argon2iSettings(m, t, p, k)
 			require.NoError(tt, err)
 			assert.True(tt, strings.HasPrefix(settings, expectSettingsPrefix))
 		}
 	}
 
-	t.Run(testFn(65536, 2, 4, "$argon2i$v=19$m=65536,t=2,p=4"))
+	t.Run(testFn(65536, 2, 4, 64, "$argon2i$v=19$m=65536,t=2,p=4,k=64"))
 }
diff --git a/argon2id.go b/argon2id.go
index 7850668..50d8ecf 100644
--- a/argon2id.go
+++ b/argon2id.go
@@ -39,13 +39,13 @@ const (
 	argon2idDefaultMemory   = 32 * 1024
 	argon2idDefaultTime     = 1
 	argon2idDefaultThreads  = 4
-	argon2idKeySize         = 32
+	argon2idDefaultKeySize  = 32
 	argon2idDefaultSaltSize = 16
 )
 
 // Argon2idSettings returns argon2id settings with the provided parameter.
-func Argon2idSettings(m, t, p int, salts ...string) (string, error) {
-	settings := fmt.Sprintf("%sv=19$m=%d,t=%d,p=%d", Argon2idPrefix, m, t, p)
+func Argon2idSettings(m, t, p, k int, salts ...string) (string, error) {
+	settings := fmt.Sprintf("%sv=19$m=%d,t=%d,p=%d,k=%d", Argon2idPrefix, m, t, p, k)
 	salt := strings.Join(salts, "")
 	if salt == "" {
 		b := make([]byte, argon2idDefaultSaltSize)
@@ -74,16 +74,31 @@ func argon2idAlgorithm(password, settings string) (string, error) {
 	memory := parameter.GetInt("m", argon2idDefaultMemory)
 	time := parameter.GetInt("t", argon2idDefaultTime)
 	threads := parameter.GetInt("p", argon2idDefaultThreads)
+	keySize := parameter.GetInt("k", argon2idDefaultKeySize)
 
-	hash := argon2.IDKey(passwordBytes, saltBytes, uint32(time), uint32(memory), uint8(threads), argon2idKeySize)
+	hash := argon2.IDKey(passwordBytes, saltBytes, uint32(time), uint32(memory), uint8(threads), uint32(keySize))
+
+	p := []string{}
+	if memory != argon2iDefaultMemory {
+		p = append(p, "m="+strconv.Itoa(memory))
+	}
+	if time != argon2iDefaultTime {
+		p = append(p, "t="+strconv.Itoa(time))
+	}
+	if threads != argon2iDefaultThreads {
+		p = append(p, "p="+strconv.Itoa(threads))
+	}
+	if keySize != argon2iDefaultKeySize {
+		p = append(p, "k="+strconv.Itoa(keySize))
+	}
 
 	buf := bytes.Buffer{}
-	buf.Write([]byte(Argon2idPrefix))
+	buf.Write([]byte(Argon2iPrefix))
 	buf.WriteString("v=19$")
-	buf.WriteString("m="+strconv.Itoa(memory)+",")
-	buf.WriteString("t="+strconv.Itoa(time)+",")
-	buf.WriteString("p="+strconv.Itoa(threads))
-	buf.WriteString("$")
+	if len(p) > 0 {
+		buf.WriteString(strings.Join(p, ","))
+		buf.WriteString("$")
+	}
 	buf.WriteString(Base64Encoding.EncodeToString(saltBytes))
 	buf.WriteString("$")
 	buf.WriteString(Base64Encoding.EncodeToString(hash))
diff --git a/argon2id_test.go b/argon2id_test.go
index cea54e5..a95e81f 100644
--- a/argon2id_test.go
+++ b/argon2id_test.go
@@ -25,74 +25,38 @@ import (
 )
 
 func TestArgon2id(t *testing.T) {
-	tcs := []struct {
-		password       string
-		settings       string
-		expectedResult string
-		expectedErr    error
-	}{
-		{
-			"generate salt",
-			"$argon2id$v=19$m=65536,t=2,p=4$",
-			"$argon2id$v=19$m=65536,t=2,p=4$",
-			nil,
-		},
-		{
-			"password", // salt = somesalt
-			"$argon2id$v=19$m=65536,t=2,p=4$c29tZXNhbHQ",
-			"$argon2id$v=19$m=65536,t=2,p=4$c29tZXNhbHQ$GpZ3sK/oH9p7VIiV56G/64Zo/8GaUw434IimaPqxwCo",
-			nil,
-		},
-		{
-			"another password", // salt = anothersalt
-			"$argon2id$v=19$m=65536,t=2,p=4$YW5vdGhlcnNhbHQ",
-			"$argon2id$v=19$m=65536,t=2,p=4$YW5vdGhlcnNhbHQ$ZU9gSnQfqeEZG2Wu6Wq9pek2UAttI/N8NLCEecVBRZc",
-			nil,
-		},
-		{
-			"password", // salt = longsaltlongsaltlong
-			"$argon2id$v=19$m=65536,t=2,p=1$bG9uZ3NhbHRsb25nc2FsdGxvbmc",
-			"$argon2id$v=19$m=65536,t=2,p=1$bG9uZ3NhbHRsb25nc2FsdGxvbmc$y3Tz6SCUIw7occvkgsUYx0hwaePXLus7rxUzsOghhnE",
-			nil,
-		},
-		{
-			"ignore-hash-in-settings", // salt = longsaltlongsaltlong
-			"$argon2id$v=19$m=65536,t=2,p=1$bG9uZ3NhbHRsb25nc2FsdGxvbmc$y3Tz6SCUIw7occvkgsUYx0hwaePXLus7rxUzsOghhnE",
-			"$argon2id$v=19$m=65536,t=2,p=1$bG9uZ3NhbHRsb25nc2FsdGxvbmc$sToxuMqIBNNRYEPy2Gh690R7qa7mkhJ627ciTZdyQSA",
-			nil,
-		},
-		{
-			"password", // salt = longsaltlongsalt
-			"$argon2id$v=19$m=65536,t=3,p=1$bG9uZ3NhbHRsb25nc2FsdA",
-			"$argon2id$v=19$m=65536,t=3,p=1$bG9uZ3NhbHRsb25nc2FsdA$SHogC8dbNGlyrOIJTrZ4f0/r/ZmTglvCx4u5GUzw6EM",
-			nil,
-		},
+	testFn := func(password, settings, expectResult string, expectErr error) (string, func(*testing.T)) {
+		return settings, func(t *testing.T) {
+			result, err := crypt.Crypt(password, settings)
+			require.Equal(t, expectErr, err)
+			assert.True(t, strings.HasPrefix(result, expectResult), "expected prefix %q, got %q", expectResult, result)
+		}
 	}
 
-	for _, tc := range tcs {
-		t.Run(tc.settings, func(t *testing.T) {
-			result, err := crypt.Crypt(tc.password, tc.settings)
-			require.Equal(t, tc.expectedErr, err)
-			assert.True(t, strings.HasPrefix(result, tc.expectedResult), "expected prefix %q, got %q", tc.expectedResult, result)
-		})
-	}
+	t.Run(testFn("generate salt", "$argon2id$v=19$m=65536,t=2,p=4$",
+		"$argon2i$v=19$m=65536,t=2$", nil))
+	t.Run(testFn("password", "$argon2id$v=19$m=65536,t=2,p=4$c29tZXNhbHQ",
+		"$argon2i$v=19$m=65536,t=2$c29tZXNhbHQ$GpZ3sK/oH9p7VIiV56G/64Zo/8GaUw434IimaPqxwCo", nil))
+	t.Run(testFn("another password", "$argon2id$v=19$m=65536,t=2,p=4$YW5vdGhlcnNhbHQ",
+		"$argon2i$v=19$m=65536,t=2$YW5vdGhlcnNhbHQ$ZU9gSnQfqeEZG2Wu6Wq9pek2UAttI/N8NLCEecVBRZc", nil))
+	t.Run(testFn("password", "$argon2id$v=19$m=65536,t=2,p=1$bG9uZ3NhbHRsb25nc2FsdGxvbmc",
+		"$argon2i$v=19$m=65536,t=2,p=1$bG9uZ3NhbHRsb25nc2FsdGxvbmc$y3Tz6SCUIw7occvkgsUYx0hwaePXLus7rxUzsOghhnE", nil))
+	t.Run(testFn("ignore-hash-in-settings", "$argon2id$v=19$m=65536,t=2,p=1$bG9uZ3NhbHRsb25nc2FsdGxvbmc$y3Tz6SCUIw7occvkgsUYx0hwaePXLus7rxUzsOghhnE",
+		"$argon2i$v=19$m=65536,t=2,p=1$bG9uZ3NhbHRsb25nc2FsdGxvbmc$sToxuMqIBNNRYEPy2Gh690R7qa7mkhJ627ciTZdyQSA", nil))
+	t.Run(testFn("password", "$argon2id$v=19$m=65536,t=3,p=1$bG9uZ3NhbHRsb25nc2FsdA",
+		"$argon2i$v=19$m=65536,t=3,p=1$bG9uZ3NhbHRsb25nc2FsdA$SHogC8dbNGlyrOIJTrZ4f0/r/ZmTglvCx4u5GUzw6EM", nil))
+	t.Run(testFn("password", "$argon2id$v=19$m=65536,t=3,p=1,k=64$bG9uZ3NhbHRsb25nc2FsdA",
+		"$argon2i$v=19$m=65536,t=3,p=1,k=64$bG9uZ3NhbHRsb25nc2FsdA$gaB/QbA34/AJkE/QbuEByjVhIF3sCvX+LHo8L3otGHhWh5q++cFMfidqGQd6qoGu3Qcm7LEPl8dQWMzyblYqYg", nil))
 }
 
 func TestArgon2idSettings(t *testing.T) {
-	tcs := []struct {
-		m                      int
-		t                      int
-		p                      int
-		expectedSettingsPrefix string
-	}{
-		{65536, 2, 4, "$argon2id$v=19$m=65536,t=2,p=4"},
+	testFn := func(m, t, p, k int, expectSettingsPrefix string) (string, func(*testing.T)) {
+		return fmt.Sprintf("m=%d,t=%d,p=%d,k=%d", m, t, p, k), func(tt *testing.T) {
+			settings, err := crypt.Argon2idSettings(m, t, p, k)
+			require.NoError(tt, err)
+			assert.True(tt, strings.HasPrefix(settings, expectSettingsPrefix))
+		}
 	}
 
-	for _, tc := range tcs {
-		t.Run(fmt.Sprintf("m=%d,t=%d,p=%d", tc.m, tc.t, tc.p), func(t *testing.T) {
-			settings, err := crypt.Argon2idSettings(tc.m, tc.t, tc.p)
-			require.NoError(t, err)
-			assert.True(t, strings.HasPrefix(settings, tc.expectedSettingsPrefix))
-		})
-	}
+	t.Run(testFn(65536, 2, 4, 64, "$argon2id$v=19$m=65536,t=2,p=4,k=64"))
 }
diff --git a/settings_test.go b/settings_test.go
index a6588dc..46f9edc 100644
--- a/settings_test.go
+++ b/settings_test.go
@@ -40,6 +40,7 @@ func TestSettings(t *testing.T) {
 	t.Run(testFn("$2a$08$ybX1Hjkb5N.8WEcYtBuB7u", "$2a$08$ybX1Hjkb5N.8WEcYtBuB7u"))
 	t.Run(testFn("$2a$08$ybX1Hjkb5N.8WEcYtBuB7u$CMA/ViizL57cnTLOa5DiVM9e", "$2a$08$ybX1Hjkb5N.8WEcYtBuB7u"))
 	t.Run(testFn("$argon2i$v=19$m=65536,t=2,p=4$c29tZXNhbHQ$IMit9qkFULCMA/ViizL57cnTLOa5DiVM9eMwpAvPwr4", "$argon2i$v=19$m=65536,t=2,p=4$c29tZXNhbHQ"))
+	t.Run(testFn("$argon2i$v=19$m=65536,t=2,p=4,k=64$c29tZXNhbHQ$IMit9qkFULCMA/ViizL57cnTLOa5DiVM9eMwpAvPwr4", "$argon2i$v=19$m=65536,t=2,p=4,k=64$c29tZXNhbHQ"))
 }
 
 func TestDecodeSettings(t *testing.T) {
@@ -62,4 +63,5 @@ func TestDecodeSettings(t *testing.T) {
 	t.Run(testFn("$1$rounds=300$salt$hash$", "1", crypt.Parameter{"rounds": "300"}, "salt", "hash", nil))
 	t.Run(testFn("$2a$08$ybX1Hjkb5N.8WEcYtBuB7u", "2a", crypt.Parameter{"cost": "8"}, "ybX1Hjkb5N.8WEcYtBuB7u", "", nil))
 	t.Run(testFn("$argon2i$v=19$m=65536,t=2,p=4$c29tZXNhbHQ$IMit9qkFULCMA/ViizL57cnTLOa5DiVM9eMwpAvPwr4", "argon2i", crypt.Parameter{"v": "19", "m": "65536", "t": "2", "p": "4"}, "c29tZXNhbHQ", "IMit9qkFULCMA/ViizL57cnTLOa5DiVM9eMwpAvPwr4", nil))
+	t.Run(testFn("$argon2i$v=19$m=65536,t=2,p=4,k=64$c29tZXNhbHQ$IMit9qkFULCMA/ViizL57cnTLOa5DiVM9eMwpAvPwr4", "argon2i", crypt.Parameter{"v": "19", "m": "65536", "t": "2", "p": "4", "k": "64"}, "c29tZXNhbHQ", "IMit9qkFULCMA/ViizL57cnTLOa5DiVM9eMwpAvPwr4", nil))
 }