diff --git a/CHANGELOG.md b/CHANGELOG.md
index 1779361..9c449db 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,10 @@
 # Changelog
 
+## Version 4.0.3 (2018-01-30)
+
+* [#72](https://github.com/paragonie/halite/issues/72): Fixed forward-compatibility with
+  libsodium 1.0.15.
+
 ## Version 4.0.2 (2017-12-08)
 
 This is mostly a boyscouting/documentation release. However, we now pass Psalm under the
diff --git a/src/KeyFactory.php b/src/KeyFactory.php
index 9a71bda..877cb66 100644
--- a/src/KeyFactory.php
+++ b/src/KeyFactory.php
@@ -135,7 +135,7 @@ public static function deriveAuthenticationKey(
         string $salt,
         string $level = self::INTERACTIVE
     ): AuthenticationKey {
-        $kdfLimits = self::getSecurityLevels($level);
+        $kdfLimits = self::getSecurityLevels($level, true);
         // VERSION 2+ (argon2)
         if (Util::safeStrlen($salt) !== \SODIUM_CRYPTO_PWHASH_SALTBYTES) {
             throw new InvalidSalt(
@@ -147,7 +147,8 @@ public static function deriveAuthenticationKey(
             $password->getString(),
             $salt,
             $kdfLimits[0],
-            $kdfLimits[1]
+            $kdfLimits[1],
+            \SODIUM_CRYPTO_PWHASH_ALG_ARGON2I13
         );
         return new AuthenticationKey(
             new HiddenString($secretKey)
@@ -172,7 +173,7 @@ public static function deriveEncryptionKey(
         string $salt,
         string $level = self::INTERACTIVE
     ): EncryptionKey {
-        $kdfLimits = self::getSecurityLevels($level);
+        $kdfLimits = self::getSecurityLevels($level, true);
         // VERSION 2+ (argon2)
         if (Util::safeStrlen($salt) !== \SODIUM_CRYPTO_PWHASH_SALTBYTES) {
             throw new InvalidSalt(
@@ -184,7 +185,8 @@ public static function deriveEncryptionKey(
             $password->getString(),
             $salt,
             $kdfLimits[0],
-            $kdfLimits[1]
+            $kdfLimits[1],
+            \SODIUM_CRYPTO_PWHASH_ALG_ARGON2I13
         );
         return new EncryptionKey(
             new HiddenString($secretKey)
@@ -208,7 +210,7 @@ public static function deriveEncryptionKeyPair(
         string $salt,
         string $level = self::INTERACTIVE
     ): EncryptionKeyPair {
-        $kdfLimits = self::getSecurityLevels($level);
+        $kdfLimits = self::getSecurityLevels($level, true);
         // VERSION 2+ (argon2)
         if (Util::safeStrlen($salt) !== \SODIUM_CRYPTO_PWHASH_SALTBYTES) {
             throw new InvalidSalt(
@@ -221,7 +223,8 @@ public static function deriveEncryptionKeyPair(
             $password->getString(),
             $salt,
             $kdfLimits[0],
-            $kdfLimits[1]
+            $kdfLimits[1],
+            \SODIUM_CRYPTO_PWHASH_ALG_ARGON2I13
         );
         $keyPair = \sodium_crypto_box_seed_keypair($seed);
         $secretKey = \sodium_crypto_box_secretkey($keyPair);
@@ -253,7 +256,7 @@ public static function deriveSignatureKeyPair(
         string $salt,
         string $level = self::INTERACTIVE
     ): SignatureKeyPair {
-        $kdfLimits = self::getSecurityLevels($level);
+        $kdfLimits = self::getSecurityLevels($level, true);
         // VERSION 2+ (argon2)
         if (Util::safeStrlen($salt) !== \SODIUM_CRYPTO_PWHASH_SALTBYTES) {
             throw new InvalidSalt(
@@ -266,7 +269,8 @@ public static function deriveSignatureKeyPair(
             $password->getString(),
             $salt,
             $kdfLimits[0],
-            $kdfLimits[1]
+            $kdfLimits[1],
+            \SODIUM_CRYPTO_PWHASH_ALG_ARGON2I13
         );
         $keyPair = \sodium_crypto_sign_seed_keypair($seed);
         $secretKey = \sodium_crypto_sign_secretkey($keyPair);
@@ -280,27 +284,38 @@ public static function deriveSignatureKeyPair(
         );
     }
 
+
     /**
      * Returns a 2D array [OPSLIMIT, MEMLIMIT] for the appropriate security level.
      *
      * @param string $level
+     * @param bool $compat
      * @return int[]
      * @throws InvalidType
      */
-    public static function getSecurityLevels(string $level = self::INTERACTIVE): array
+    public static function getSecurityLevels(string $level = self::INTERACTIVE, bool $compat = false): array
     {
         switch ($level) {
             case self::INTERACTIVE:
+                if ($compat) {
+                    return [4, 33554432];
+                }
                 return [
                     \SODIUM_CRYPTO_PWHASH_OPSLIMIT_INTERACTIVE,
                     \SODIUM_CRYPTO_PWHASH_MEMLIMIT_INTERACTIVE
                 ];
             case self::MODERATE:
+                if ($compat) {
+                    return [6, 134217728];
+                }
                 return [
                     \SODIUM_CRYPTO_PWHASH_OPSLIMIT_MODERATE,
                     \SODIUM_CRYPTO_PWHASH_MEMLIMIT_MODERATE
                 ];
             case self::SENSITIVE:
+                if ($compat) {
+                    return [8, 536870912];
+                }
                 return [
                     \SODIUM_CRYPTO_PWHASH_OPSLIMIT_SENSITIVE,
                     \SODIUM_CRYPTO_PWHASH_MEMLIMIT_SENSITIVE
diff --git a/src/Password.php b/src/Password.php
index 85e7d19..312817c 100644
--- a/src/Password.php
+++ b/src/Password.php
@@ -3,6 +3,7 @@
 namespace ParagonIE\Halite;
 
 use ParagonIE\ConstantTime\Base64UrlSafe;
+use ParagonIE\ConstantTime\Binary;
 use ParagonIE\ConstantTime\Hex;
 use ParagonIE\Halite\Alerts\{
     CannotPerformOperation,
@@ -108,7 +109,10 @@ public static function needsRehash(
         // Upon successful decryption, verify that we're using Argon2i
         if (!\hash_equals(
             Util::safeSubstr($hash_str, 0, 9),
-            \SODIUM_CRYPTO_PWHASH_STRPREFIX
+            '$argon2i$'
+        ) && !\hash_equals(
+            Util::safeSubstr($hash_str, 0, 10),
+            '$argon2id$'
         )) {
             return true;
         }
@@ -119,16 +123,25 @@ public static function needsRehash(
                 return !\hash_equals(
                     '$argon2i$v=19$m=32768,t=4,p=1$',
                     Util::safeSubstr($hash_str, 0, 30)
+                ) && !\hash_equals(
+                    '$argon2id$v=19$m=65536,t=2,p=1$',
+                    Util::safeSubstr($hash_str, 0, 31)
                 );
             case KeyFactory::MODERATE:
                 return !\hash_equals(
                     '$argon2i$v=19$m=131072,t=6,p=1$',
                     Util::safeSubstr($hash_str, 0, 31)
+                ) && !\hash_equals(
+                    '$argon2id$v=19$m=262144,t=3,p=1$',
+                    Util::safeSubstr($hash_str, 0, 32)
                 );
             case KeyFactory::SENSITIVE:
                 return !\hash_equals(
                     '$argon2i$v=19$m=524288,t=8,p=1$',
                     Util::safeSubstr($hash_str, 0, 31)
+                ) && !\hash_equals(
+                    '$argon2id$v=19$m=1048576,t=4,p=1',
+                    Util::safeSubstr($hash_str, 0, 33)
                 );
             default:
                 return true;