diff --git a/phpseclib/File/ASN1.php b/phpseclib/File/ASN1.php
index 3aaa3090..8a7286b1 100644
--- a/phpseclib/File/ASN1.php
+++ b/phpseclib/File/ASN1.php
@@ -702,7 +702,14 @@ class ASN1
                 return isset($this->oids[$decoded['content']]) ? $this->oids[$decoded['content']] : $decoded['content'];
             case self::TYPE_UTC_TIME:
             case self::TYPE_GENERALIZED_TIME:
-                if (isset($mapping['implicit'])) {
+                // for explicitly tagged optional stuff
+                if (is_array($decoded['content'])) {
+                    $decoded['content'] = $decoded['content'][0]['content'];
+                }
+                // for implicitly tagged optional stuff
+                // in theory, doing isset($mapping['implicit']) would work but malformed certs do exist
+                // in the wild that OpenSSL decodes without issue so we'll support them as well
+                if (!is_object($decoded['content'])) {
                     $decoded['content'] = $this->_decodeTime($decoded['content'], $decoded['type']);
                 }
                 return $decoded['content'] ? $decoded['content']->format($this->format) : false;
diff --git a/phpseclib/File/X509.php b/phpseclib/File/X509.php
index 78d0e91d..b4963fc8 100644
--- a/phpseclib/File/X509.php
+++ b/phpseclib/File/X509.php
@@ -963,6 +963,13 @@ class X509
             'children' => $AccessDescription
         );
 
+        $this->SubjectInfoAccessSyntax = array(
+            'type'     => ASN1::TYPE_SEQUENCE,
+            'min'      => 1,
+            'max'      => -1,
+            'children' => $AccessDescription
+        );
+
         $this->SubjectAltName = $GeneralNames;
 
         $this->PrivateKeyUsagePeriod = array(
@@ -1892,6 +1899,8 @@ class X509
                 return $this->ExtKeyUsageSyntax;
             case 'id-pe-authorityInfoAccess':
                 return $this->AuthorityInfoAccessSyntax;
+            case 'id-pe-subjectInfoAccess':
+                return $this->SubjectInfoAccessSyntax;
             case 'id-ce-subjectAltName':
                 return $this->SubjectAltName;
             case 'id-ce-subjectDirectoryAttributes':
diff --git a/tests/Unit/File/ASN1Test.php b/tests/Unit/File/ASN1Test.php
index 6c8c3175..b75333b7 100644
--- a/tests/Unit/File/ASN1Test.php
+++ b/tests/Unit/File/ASN1Test.php
@@ -363,4 +363,33 @@ class Unit_File_ASN1Test extends PhpseclibTestCase
         $this->assertSame(pack('H*', '6983f09da7ebcfdee0c7a1a7b2c0948cc8f9d776'), $new);
         $this->assertSame($orig, $asn1->_decodeOID($new));
     }
+
+    /**
+     * @group github1388
+     */
+    public function testExplicitImplicitDate()
+    {
+        $map = [
+            'type'     => ASN1::TYPE_SEQUENCE,
+            'children' => [
+                'notBefore' => [
+                                             'constant' => 0,
+                                             'optional' => true,
+                                             'implicit' => true,
+                                             'type' => ASN1::TYPE_GENERALIZED_TIME],
+                'notAfter'  => [
+                                             'constant' => 1,
+                                             'optional' => true,
+                                             'implicit' => true,
+                                             'type' => ASN1::TYPE_GENERALIZED_TIME]
+            ]
+        ];
+
+        $asn1 = new ASN1();
+        $a = pack('H*', '3026a011180f32303137303432313039303535305aa111180f32303138303432313230353935395a');
+        $a = $asn1->decodeBER($a);
+        $a = $asn1->asn1map($a[0], $map);
+
+        $this->assertInternalType('array', $a);
+    }
 }