diff --git a/TwoFactorAuth.phpproj b/TwoFactorAuth.phpproj
index c17df88..76a1830 100644
--- a/TwoFactorAuth.phpproj
+++ b/TwoFactorAuth.phpproj
@@ -30,6 +30,7 @@
     <Compile Include="lib\Providers\Qr\QRException.php" />
     <Compile Include="lib\Providers\Qr\QRicketProvider.php" />
     <Compile Include="lib\Providers\Qr\QRServerProvider.php" />
+    <Compile Include="lib\Providers\Rng\CSRNGProvider.php" />
     <Compile Include="lib\Providers\Rng\IRNGProvider.php" />
     <Compile Include="lib\Providers\Rng\MCryptRNGProvider.php" />
     <Compile Include="lib\Providers\Rng\OpenSSLRNGProvider.php" />
diff --git a/composer.json b/composer.json
index c73bb07..43fa999 100644
--- a/composer.json
+++ b/composer.json
@@ -1,7 +1,7 @@
 {
     "name": "robthree/twofactorauth",
     "description": "Two Factor Authentication",
-    "version": "1.3",
+    "version": "1.4",
     "type": "library",
     "keywords": [ "Authentication", "Two Factor Authentication", "Multi Factor Authentication", "TFA", "MFA", "PHP", "Authenticator", "Authy" ],
     "homepage": "https://github.com/RobThree/TwoFactorAuth",
diff --git a/lib/Providers/Qr/QRServerProvider.php b/lib/Providers/Qr/QRServerProvider.php
index 87717f1..2d889f9 100644
--- a/lib/Providers/Qr/QRServerProvider.php
+++ b/lib/Providers/Qr/QRServerProvider.php
@@ -43,6 +43,7 @@ class QRServerProvider extends BaseHTTPQRCodeProvider
         	case 'eps':
                 return 'application/postscript';
         }
+        throw new QRException(sprintf('Unknown MIME-type: %s', $this->format));
     }
     
     public function getQRCodeImage($qrtext, $size) 
diff --git a/lib/Providers/Qr/QRicketProvider.php b/lib/Providers/Qr/QRicketProvider.php
index b6aed5a..e2f404b 100644
--- a/lib/Providers/Qr/QRicketProvider.php
+++ b/lib/Providers/Qr/QRicketProvider.php
@@ -33,6 +33,7 @@ class QRicketProvider extends BaseHTTPQRCodeProvider
         	case 'j':
                 return 'image/jpeg';
         }
+        throw new QRException(sprintf('Unknown MIME-type: %s', $this->format));
     }
     
     public function getQRCodeImage($qrtext, $size) 
diff --git a/lib/Providers/Rng/CSRNGProvider.php b/lib/Providers/Rng/CSRNGProvider.php
new file mode 100644
index 0000000..8dba7fc
--- /dev/null
+++ b/lib/Providers/Rng/CSRNGProvider.php
@@ -0,0 +1,14 @@
+<?php
+
+namespace RobThree\Auth\Providers\Rng;
+
+class CSRNGProvider implements IRNGProvider
+{
+    public function getRandomBytes($bytecount) {
+        return random_bytes($bytecount);    // PHP7+
+    }
+    
+    public function isCryptographicallySecure() {
+        return true;
+    }
+}
\ No newline at end of file
diff --git a/lib/TwoFactorAuth.php b/lib/TwoFactorAuth.php
index a2e4132..e70d1d8 100644
--- a/lib/TwoFactorAuth.php
+++ b/lib/TwoFactorAuth.php
@@ -45,7 +45,9 @@ class TwoFactorAuth
         
         // Try to find best available RNG provider if none was specified
         if ($rngprovider==null) {
-            if (function_exists('mcrypt_create_iv')) {
+            if (function_exists('random_bytes')) {
+                $rngprovider = new Providers\Rng\CSRNGProvider();
+            } elseif (function_exists('mcrypt_create_iv')) {
                 $rngprovider = new Providers\Rng\MCryptRNGProvider();
             } elseif (function_exists('openssl_random_pseudo_bytes')) {
                 $rngprovider = new Providers\Rng\OpenSSLRNGProvider();
diff --git a/tests/TwoFactorAuthTest.php b/tests/TwoFactorAuthTest.php
index a0c381b..89f1ac0 100644
--- a/tests/TwoFactorAuthTest.php
+++ b/tests/TwoFactorAuthTest.php
@@ -24,7 +24,7 @@ class TwoFactorAuthTest extends PHPUnit_Framework_TestCase
      */
     public function testConstructorThrowsOnInvalidDigits() {
 
-        $tfa = new TwoFactorAuth('Test', 0);
+        new TwoFactorAuth('Test', 0);
     }
 
     /**
@@ -32,7 +32,7 @@ class TwoFactorAuthTest extends PHPUnit_Framework_TestCase
      */
     public function testConstructorThrowsOnInvalidPeriod() {
 
-        $tfa = new TwoFactorAuth('Test', 6, 0);
+        new TwoFactorAuth('Test', 6, 0);
     }
 
     /**
@@ -40,7 +40,7 @@ class TwoFactorAuthTest extends PHPUnit_Framework_TestCase
      */
     public function testConstructorThrowsOnInvalidAlgorithm() {
 
-        $tfa = new TwoFactorAuth('Test', 6, 30, 'xxx');
+        new TwoFactorAuth('Test', 6, 30, 'xxx');
     }
 
     /**
@@ -48,7 +48,7 @@ class TwoFactorAuthTest extends PHPUnit_Framework_TestCase
      */
     public function testConstructorThrowsOnQrProviderNotImplementingInterface() {
 
-        $tfa = new TwoFactorAuth('Test', 6, 30, 'sha1', new stdClass());
+        new TwoFactorAuth('Test', 6, 30, 'sha1', new stdClass());
     }
 
     /**
@@ -56,7 +56,7 @@ class TwoFactorAuthTest extends PHPUnit_Framework_TestCase
      */
     public function testConstructorThrowsOnRngProviderNotImplementingInterface() {
 
-        $tfa = new TwoFactorAuth('Test', 6, 30, 'sha1', null, new stdClass());
+        new TwoFactorAuth('Test', 6, 30, 'sha1', null, new stdClass());
     }
 
     public function testGetCodeReturnsCorrectResults() {
@@ -147,7 +147,7 @@ class TwoFactorAuthTest extends PHPUnit_Framework_TestCase
      */
     public function testGetCodeThrowsOnInvalidBase32String1() {
         $tfa = new TwoFactorAuth('Test');
-        $result = $tfa->getCode('FOO1BAR8BAZ9');    //1, 8 & 9 are invalid chars
+        $tfa->getCode('FOO1BAR8BAZ9');    //1, 8 & 9 are invalid chars
     }
     
     /**
@@ -155,7 +155,7 @@ class TwoFactorAuthTest extends PHPUnit_Framework_TestCase
      */
     public function testGetCodeThrowsOnInvalidBase32String2() {
         $tfa = new TwoFactorAuth('Test');
-        $result = $tfa->getCode('mzxw6===');        //Lowercase
+        $tfa->getCode('mzxw6===');        //Lowercase
     }
     
     public function testKnownBase32DecodeTestVectors() {
@@ -242,7 +242,62 @@ class TwoFactorAuthTest extends PHPUnit_Framework_TestCase
         $this->assertEquals('47863826', $tfa->getCode($secret, 20000000000));
     }
 
+    /**
+     * @requires function random_bytes
+     */
+    public function testCSRNGProvidersReturnExpectedNumberOfBytes() {
+        $rng = new \RobThree\Auth\Providers\Rng\CSRNGProvider();
+        foreach ($this->getRngTestLengths() as $l)
+            $this->assertEquals($l, strlen($rng->getRandomBytes($l)));
+        $this->assertEquals(true, $rng->isCryptographicallySecure());
+    }
+
+    /**
+     * @requires function hash_algos
+     * @requires function hash
+     */
+    public function testHashRNGProvidersReturnExpectedNumberOfBytes() {
+        $rng = new \RobThree\Auth\Providers\Rng\HashRNGProvider();
+        foreach ($this->getRngTestLengths() as $l)
+            $this->assertEquals($l, strlen($rng->getRandomBytes($l)));
+        $this->assertEquals(false, $rng->isCryptographicallySecure());
+    }
     
+    /**
+     * @requires function mcrypt_create_iv
+     */
+    public function testMCryptRNGProvidersReturnExpectedNumberOfBytes() {
+        $rng = new \RobThree\Auth\Providers\Rng\MCryptRNGProvider();
+        foreach ($this->getRngTestLengths() as $l)
+            $this->assertEquals($l, strlen($rng->getRandomBytes($l)));
+        $this->assertEquals(true, $rng->isCryptographicallySecure());
+    }
+
+    /**
+     * @requires function openssl_random_pseudo_bytes
+     */
+    public function testStrongOpenSSLRNGProvidersReturnExpectedNumberOfBytes() {
+        $rng = new \RobThree\Auth\Providers\Rng\OpenSSLRNGProvider(true);
+        foreach ($this->getRngTestLengths() as $l)
+            $this->assertEquals($l, strlen($rng->getRandomBytes($l)));
+        $this->assertEquals(true, $rng->isCryptographicallySecure());
+    }
+
+    /**
+     * @requires function openssl_random_pseudo_bytes
+     */
+    public function testNonStrongOpenSSLRNGProvidersReturnExpectedNumberOfBytes() {
+        $rng = new \RobThree\Auth\Providers\Rng\OpenSSLRNGProvider(false);
+        foreach ($this->getRngTestLengths() as $l)
+            $this->assertEquals($l, strlen($rng->getRandomBytes($l)));
+        $this->assertEquals(false, $rng->isCryptographicallySecure());
+    }
+
+
+    private function getRngTestLengths() {
+        return array(1, 16, 32, 256);
+    }
+
     private function DecodeDataUri($datauri) {
         if (preg_match('/data:(?P<mimetype>[\w\.\-\/]+);(?P<encoding>\w+),(?P<data>.*)/', $datauri, $m) === 1) {
             return array(