diff --git a/phpseclib/Crypt/RSA/PublicKey.php b/phpseclib/Crypt/RSA/PublicKey.php
index 4adf3b89..a0b47e28 100644
--- a/phpseclib/Crypt/RSA/PublicKey.php
+++ b/phpseclib/Crypt/RSA/PublicKey.php
@@ -212,7 +212,7 @@ class PublicKey extends RSA implements Common\PublicKey
         // if $m is larger than two million terrabytes and you're using sha1, PKCS#1 suggests a "Label too long" error
         // be output.
 
-        $emLen = ($emBits + 1) >> 3; // ie. ceil($emBits / 8);
+        $emLen = ($emBits + 7) >> 3; // ie. ceil($emBits / 8);
         $sLen = $this->sLen !== null ? $this->sLen : $this->hLen;
 
         $mHash = $this->hash->hash($m);
@@ -263,11 +263,11 @@ class PublicKey extends RSA implements Common\PublicKey
 
         // RSA verification
 
-        $modBits = 8 * $this->k;
+        $modBits = strlen($this->modulus->toBits());
 
         $s2 = $this->os2ip($s);
         $m2 = $this->rsavp1($s2);
-        $em = $this->i2osp($m2, $modBits >> 3);
+        $em = $this->i2osp($m2, $this->k);
         if ($em === false) {
             return false;
         }
diff --git a/tests/Unit/Crypt/RSA/ModeTest.php b/tests/Unit/Crypt/RSA/ModeTest.php
index e4bc304a..f2cb4e5a 100644
--- a/tests/Unit/Crypt/RSA/ModeTest.php
+++ b/tests/Unit/Crypt/RSA/ModeTest.php
@@ -132,4 +132,27 @@ U9VQQSQzY1oZMVX8i1m5WUTLPz2yLJIBQVdXqhMCQBGoiuSoSjafUhV7i1cEGpb88h5NBYZzWXGZ
         $rsa = $rsa->getPublicKey();
         $this->assertTrue($rsa->verify($plaintext, $sig));
     }
+
+    /**
+     * @group github1423
+     */
+    public function testPSSSigsWithNonPowerOf2Key()
+    {
+        $pub = <<<HERE
+-----BEGIN PUBLIC KEY-----
+MF0wDQYJKoZIhvcNAQEBBQADTAAwSQJCAmdYuOvii3I6ya3q/zSeZFoJprgF9fIq
+k12yS6pCS3c+1wZ9cYFVtgfpSL4XpylLe9EnRT2GRVYCqUkR4AUeTuvnAgMBAAE=
+-----END PUBLIC KEY-----
+HERE;
+
+        $rsa = PublicKeyLoader::load($pub)
+            ->withHash('sha256')
+            ->withSaltLength(32)
+            ->withMGFHash('sha256');
+
+        $sig = base64_decode(strtr('Ad022bD-UCmWpBNMtsYJjG0FVxML-FFlN4IKrByP8rwjVzV_D-YqSjc_oW6LrooV7jbtEF5803YLn8lllyzDnw00', '-_', '+/'));
+
+        $payload = 'eyJraWQiOiJ0RkMyVUloRnBUTV9FYTNxY09kX01xUVQxY0JCbTlrRkxTRGZlSmhzUkc4IiwiYWxnIjoiUFMyNTYifQ.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';
+        $this->assertTrue($rsa->verify($payload, $sig));
+    }
 }