diff --git a/tests/Math/BigInteger/TestCase.php b/tests/Math/BigInteger/TestCase.php
index ea9d4e2b..d62dcec5 100644
--- a/tests/Math/BigInteger/TestCase.php
+++ b/tests/Math/BigInteger/TestCase.php
@@ -265,4 +265,69 @@ abstract class Math_BigInteger_TestCase extends PhpseclibTestCase
         $this->assertSame('18446744073709551616', (string) $x);
         $this->assertSame('18446744073709551616', (string) $y);
     }
+
+    /**
+    * @group github279
+    */
+    public function testDiffieHellmanKeyAgreement()
+    {
+        if (getenv('TRAVIS') && PHP_VERSION === '5.3.3'
+            && MATH_BIGINTEGER_MODE === MATH_BIGINTEGER_MODE_INTERNAL
+        ) {
+            $this->markTestIncomplete(
+                'This test hangs on PHP 5.3.3 using internal mode.'
+            );
+        }
+
+        // "Oakley Group 14" 2048-bit modular exponentiation group as used in
+        // SSH2 diffie-hellman-group14-sha1
+        $prime = $this->getInstance(
+            'FFFFFFFFFFFFFFFFC90FDAA22168C234C4C6628B80DC1CD1' .
+            '29024E088A67CC74020BBEA63B139B22514A08798E3404DD' .
+            'EF9519B3CD3A431B302B0A6DF25F14374FE1356D6D51C245' .
+            'E485B576625E7EC6F44C42E9A637ED6B0BFF5CB6F406B7ED' .
+            'EE386BFB5A899FA5AE9F24117C4B1FE649286651ECE45B3D' .
+            'C2007CB8A163BF0598DA48361C55D39A69163FA8FD24CF5F' .
+            '83655D23DCA3AD961C62F356208552BB9ED529077096966D' .
+            '670C354E4ABC9804F1746C08CA18217C32905E462E36CE3B' .
+            'E39E772C180E86039B2783A2EC07A28FB5C55DF06F4C52C9' .
+            'DE2BCBF6955817183995497CEA956AE515D2261898FA0510' .
+            '15728E5A8AACAA68FFFFFFFFFFFFFFFF',
+            16
+        );
+        $generator = $this->getInstance(2);
+
+        /*
+        Code for generation of $alicePrivate and $bobPrivate.
+        $one = $this->getInstance(1);
+        $max = $one->bitwise_leftShift(512)->subtract($one);
+        $alicePrivate = $one->random($one, $max);
+        $bobPrivate = $one->random($one, $max);
+        var_dump($alicePrivate->toHex(), $bobPrivate->toHex());
+        */
+
+        $alicePrivate = $this->getInstance(
+            '22606EDA7960458BC9D65F46DD96F114F9A004F0493C1F26' .
+            '2139D2C8063B733162E876182CA3BF063AB1A167ABDB7F03' .
+            'E0A225A6205660439F6CE46D252069FF',
+            16
+        );
+        $bobPrivate = $this->getInstance(
+            '6E3EFA13A96025D63E4B0D88A09B3A46DDFE9DD3BC9D1655' .
+            '4898C02B4AC181F0CEB4E818664B12F02C71A07215C400F9' .
+            '88352A4779F3E88836F7C3D3B3C739DE',
+            16
+        );
+
+        $alicePublic = $generator->modPow($alicePrivate, $prime);
+        $bobPublic =  $generator->modPow($bobPrivate, $prime);
+
+        $aliceShared = $bobPublic->modPow($alicePrivate, $prime);
+        $bobShared = $alicePublic->modPow($bobPrivate, $prime);
+
+        $this->assertTrue(
+            $aliceShared->equals($bobShared),
+            'Failed asserting that Alice and Bob share the same BigInteger.'
+        );
+    }
 }