diff --git a/.travis.yml b/.travis.yml
index 9e8c6cb..de853f0 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -33,7 +33,7 @@ matrix:
 
 install:
   - composer self-update
-  - if [[ $USE_PSALM -eq 1 ]]; then composer require --dev "vimeo/psalm:^1|^2"; fi
+  - if [[ $USE_PSALM -eq 1 ]]; then composer require --dev "vimeo/psalm:^1|^3"; fi
   - composer update
 
 script:
diff --git a/composer.json b/composer.json
index 3db077f..5124931 100644
--- a/composer.json
+++ b/composer.json
@@ -33,7 +33,7 @@
   },
   "require-dev": {
     "composer/composer": "^1",
-    "phpunit/phpunit": "^4|^5|^6"
+    "phpunit/phpunit": "^4|^5|^6|^7"
   },
   "scripts": {
     "post-autoload-dump": [
diff --git a/src/Bundle.php b/src/Bundle.php
index faf3c47..81af42b 100644
--- a/src/Bundle.php
+++ b/src/Bundle.php
@@ -68,6 +68,7 @@ public function __construct(
         $this->signature = $signature;
         $this->chronicleHash = $chronicleHash;
         if (!empty($customValidator)) {
+            /** @psalm-suppress MixedMethodCall */
             if (\class_exists($customValidator)) {
                 $newClass = new $customValidator();
                 if (!($newClass instanceof Validator)) {
@@ -177,6 +178,8 @@ public function getChronicleHash()
      *
      * @return Validator
      * @throws CertaintyException
+     *
+     * @psalm-suppress DocblockTypeContradiction
      */
     public function getValidator()
     {
diff --git a/src/LocalCACertBuilder.php b/src/LocalCACertBuilder.php
index a4f44ee..121b20c 100644
--- a/src/LocalCACertBuilder.php
+++ b/src/LocalCACertBuilder.php
@@ -8,6 +8,7 @@
 use ParagonIE\Certainty\Exception\FilesystemException;
 use ParagonIE\Certainty\Exception\InvalidResponseException;
 use ParagonIE\ConstantTime\Base64UrlSafe;
+use ParagonIE\ConstantTime\Binary;
 use ParagonIE\ConstantTime\Hex;
 
 /**
@@ -226,6 +227,8 @@ public function getPublicKey($raw = false)
      * @return bool
      * @throws CertaintyException
      * @throws \SodiumException
+     *
+     * @psalm-suppress RedundantConditionGivenDocblockType
      */
     public function save()
     {
@@ -311,9 +314,9 @@ public function setChronicle(
         $clientId = '',
         $repository = 'paragonie/certainty'
     ) {
-        if (\ParagonIE_Sodium_Core_Util::strlen($publicKey) === 64) {
+        if (Binary::safeStrlen($publicKey) === 64) {
             $publicKey = Hex::decode($publicKey);
-        } elseif (\ParagonIE_Sodium_Core_Util::strlen($publicKey) !== 32) {
+        } elseif (Binary::safeStrlen($publicKey) !== 32) {
             throw new CryptoException(
                 'Signing secret keys must be SODIUM_CRYPTO_SIGN_PUBLICKEYBYTES bytes long.'
             );
@@ -332,6 +335,8 @@ public function setChronicle(
      * @param string $string
      * @return self
      * @throws \TypeError
+     *
+     * @psalm-suppress MixedMethodCall
      */
     public function setCustomValidator($string = '')
     {
@@ -381,9 +386,9 @@ public function setOutputJsonFile($string = '')
     public function setSigningKey($secretKey = '')
     {
         // Handle hex-encoded strings.
-        if (\ParagonIE_Sodium_Core_Util::strlen($secretKey) === 128) {
+        if (Binary::safeStrlen($secretKey) === 128) {
             $secretKey = Hex::decode($secretKey);
-        } elseif (\ParagonIE_Sodium_Core_Util::strlen($secretKey) !== 64) {
+        } elseif (Binary::safeStrlen($secretKey) !== 64) {
             throw new CryptoException(
                 'Signing secret keys must be SODIUM_CRYPTO_SIGN_SECRETKEYBYTES bytes long.'
             );
diff --git a/src/Validator.php b/src/Validator.php
index 43c43f9..caa44a7 100644
--- a/src/Validator.php
+++ b/src/Validator.php
@@ -190,7 +190,7 @@ public function checkChronicleHash(Bundle $bundle)
             $ok = false;
         }
         if (!$ok) {
-            if (self::THROW_MORE_EXCEPTIONS) {
+            if (static::THROW_MORE_EXCEPTIONS) {
                 if (isset($json['error'])) {
                     /** @var string $jsonError */
                     $jsonError = $json['error'];