diff --git a/phpseclib/Math/BigInteger.php b/phpseclib/Math/BigInteger.php
index 8d1291db..81b69ace 100644
--- a/phpseclib/Math/BigInteger.php
+++ b/phpseclib/Math/BigInteger.php
@@ -408,7 +408,7 @@ class BigInteger
                     $x = substr($x, 1);
                 }
 
-                $x = preg_replace('#^(?:0x)?([A-Fa-f0-9]*).*#', '$1', $x);
+                $x = preg_replace('#^(?:0x)?([A-Fa-f0-9]*).*#s', '$1', $x);
 
                 $is_negative = false;
                 if ($base < 0 && hexdec($x[0]) >= 8) {
@@ -444,7 +444,7 @@ class BigInteger
                 // (?<!^)(?:-).*: find any -'s that aren't at the beginning and then any characters that follow that
                 // (?<=^|-)0*: find any 0's that are preceded by the start of the string or by a - (ie. octals)
                 // [^-0-9].*: find any non-numeric characters and then any characters that follow that
-                $x = preg_replace('#(?<!^)(?:-).*|(?<=^|-)0*|[^-0-9].*#', '', $x);
+                $x = preg_replace('#(?<!^)(?:-).*|(?<=^|-)0*|[^-0-9].*#s', '', $x);
                 if (!strlen($x) || $x == '-') {
                     $x = '0';
                 }
@@ -486,7 +486,7 @@ class BigInteger
                     $x = substr($x, 1);
                 }
 
-                $x = preg_replace('#^([01]*).*#', '$1', $x);
+                $x = preg_replace('#^([01]*).*#s', '$1', $x);
                 $x = str_pad($x, strlen($x) + (3 * strlen($x)) % 4, 0, STR_PAD_LEFT);
 
                 $str = '0x';
diff --git a/tests/Unit/Math/BigInteger/TestCase.php b/tests/Unit/Math/BigInteger/TestCase.php
index fb7fbbeb..e2f6dab6 100644
--- a/tests/Unit/Math/BigInteger/TestCase.php
+++ b/tests/Unit/Math/BigInteger/TestCase.php
@@ -459,7 +459,7 @@ FFBD504C5A756A2E6BB5CECC13BCA7503F6DF8B52ACE5C410997E98809DB4DC30D943DE4E81
 2A47553DCE54844A78E36401D13F77DC650619FED88D8B3926E3D8E319C80C744779AC5D6AB
 E252896950917476ECE5E8FC27D5F053D6018D91B502C4787558A002B9283DA7', 16);
 
-        $y = $this->getInstance('0xE932AC92252F585B3A80A4DD76A897C8B7652952FE788F6EC8DD640587A1EE5647670A8AD');
-        $this->assertSame($x, $y);
+        $y = $this->getInstance('0xE932AC92252F585B3A80A4DD76A897C8B7652952FE788F6EC8DD640587A1EE5647670A8AD', 16);
+        $this->assertSame("$x", "$y");
     }
 }