diff --git a/phpseclib/File/ASN1.php b/phpseclib/File/ASN1.php
index cf23dd73..3096ff1a 100644
--- a/phpseclib/File/ASN1.php
+++ b/phpseclib/File/ASN1.php
@@ -1402,7 +1402,7 @@ abstract class ASN1
                         return false;
                     }
                     break;
-                case ($c & 0x80000000) != 0:
+                case ($c & (PHP_INT_SIZE == 8 ? 0x80000000 : (1 << 31))) != 0:
                     return false;
                 case $c >= 0x04000000:
                     $v .= chr(0x80 | ($c & 0x3F));