diff --git a/src/PHPMailer.php b/src/PHPMailer.php
index b710ab80..478fae91 100644
--- a/src/PHPMailer.php
+++ b/src/PHPMailer.php
@@ -708,10 +708,13 @@ class PHPMailer
 
     /**
      * The lower maximum line length allowed by RFC 2822 section 2.1.1.
+     * This length does NOT include the line break
+     * 76 means that lines will be 77 or 78 chars depending on whether
+     * the line break format is LF or CRLF; both are valid.
      *
      * @var int
      */
-    const STD_LINE_LENGTH = 78;
+    const STD_LINE_LENGTH = 76;
 
     /**
      * Constructor.
@@ -2956,7 +2959,7 @@ class PHPMailer
             case 'base64':
                 $encoded = chunk_split(
                     base64_encode($str),
-                    static::STD_LINE_LENGTH - strlen(static::$LE),
+                    static::STD_LINE_LENGTH,
                     static::$LE
                 );
                 break;
diff --git a/test/PHPMailerTest.php b/test/PHPMailerTest.php
index 52adedd9..0ac6e38e 100644
--- a/test/PHPMailerTest.php
+++ b/test/PHPMailerTest.php
@@ -862,16 +862,21 @@ final class PHPMailerTest extends TestCase
         $noencode = 'eeeeeeeeee';
         $this->Mail->isMail();
         //Expected results
-        $bencoderes = '=?UTF-8?B?w6nDqcOpw6nDqcOpw6nDqcOpw6nDqcOpw6nDqcOpw6nDqcOpw6nDqcOpw6k=?=' . PHPMailer::getLE() .
-            ' =?UTF-8?B?w6nDqcOpw6nDqcOpw6nDqcOpw6nDqcOpw6nDqcOpw6nDqcOpw6nDqcOpw6k=?=' . PHPMailer::getLE() .
-            ' =?UTF-8?B?w6nDqcOpw6nDqcOpw6nDqcOpw6nDqcOpw6nDqcOpw6nDqcOpw6nDqcOpw6k=?=' . PHPMailer::getLE() .
-            ' =?UTF-8?B?w6nDqcOpw6nDqcOpw6nDqcOpw6nDqcOpw6k=?=';
-        $qencoderes = '=?UTF-8?Q?eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee?=' . PHPMailer::getLE() .
+
+        $bencoderes = '=?UTF-8?B?w6nDqcOpw6nDqcOpw6nDqcOpw6nDqcOpw6nDqcOpw6nDqcOpw6nDqcOpw6k=?=' .
+            PHPMailer::getLE() .
+            ' =?UTF-8?B?w6nDqcOpw6nDqcOpw6nDqcOpw6nDqcOpw6nDqcOpw6nDqcOpw6nDqcOpw6k=?=' .
+            PHPMailer::getLE() .
+            ' =?UTF-8?B?w6nDqcOpw6nDqcOpw6nDqcOpw6nDqcOpw6nDqcOpw6nDqcOpw6nDqcOpw6k=?=' .
+            PHPMailer::getLE() .
+            ' =?UTF-8?B?w6nDqcOpw6nDqcOpw6nDqcOpw6nDqQ==?=';
+        $qencoderes = '=?UTF-8?Q?eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee?=' .
+            PHPMailer::getLE() .
             ' =?UTF-8?Q?eeeeeeeeeeeeeeeeeeeeeeeeee=C3=A9?=';
         $bencodenofoldres = '=?UTF-8?B?w6nDqcOpw6nDqcOpw6nDqcOpw6k=?=';
         $qencodenofoldres = '=?UTF-8?Q?eeeeeeeee=C3=A9?=';
-        $justfoldres = 'eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee' .
-            'eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee' . PHPMailer::getLE() . ' eeeeeeeeee';
+        $justfoldres = 'eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee' .
+            PHPMailer::getLE() . ' eeeeeeeeee';
         $noencoderes = 'eeeeeeeeee';
         $this->assertEquals(
             $bencoderes,