diff --git a/phpseclib/Math/BigInteger.php b/phpseclib/Math/BigInteger.php
index ed28c78c..36e6ce99 100644
--- a/phpseclib/Math/BigInteger.php
+++ b/phpseclib/Math/BigInteger.php
@@ -2694,7 +2694,14 @@ class BigInteger
     {
         switch (MATH_BIGINTEGER_MODE) {
             case self::MODE_GMP:
-                return gmp_cmp($this->value, $y->value);
+                $r = gmp_cmp($this->value, $y->value);
+                if ($r < -1) {
+                    $r = -1;
+                }
+                if ($r > 1) {
+                    $r = 1;
+                }
+                return $r;
             case self::MODE_BCMATH:
                 return bccomp($this->value, $y->value, 0);
         }
diff --git a/tests/Unit/Math/BigInteger/TestCase.php b/tests/Unit/Math/BigInteger/TestCase.php
index 0b9ef016..92c72222 100644
--- a/tests/Unit/Math/BigInteger/TestCase.php
+++ b/tests/Unit/Math/BigInteger/TestCase.php
@@ -182,6 +182,9 @@ abstract class Unit_Math_BigInteger_TestCase extends PhpseclibTestCase
         // c < d
         $this->assertLessThan(0, $c->compare($d));
         $this->assertGreaterThan(0, $d->compare($c));
+
+        $this->assertSame(-1, $this->getInstance(-999)->compare($this->getInstance(370)));
+        $this->assertSame(1, $this->getInstance(999)->compare($this->getInstance(-700)));
     }
 
     public function testBitwiseAND()