diff --git a/src/Phar.php b/src/Phar.php
index cec050a..5c05fa4 100644
--- a/src/Phar.php
+++ b/src/Phar.php
@@ -19,9 +19,10 @@
 
 function php_strip_whitespace($file): string
 {
+    $lines = file($file, FILE_IGNORE_NEW_LINES);
+
     // First pass, process inline comments
     // We need to rely on the LF chars here
-    $lines = file($file, FILE_IGNORE_NEW_LINES);
     $lines = array_map(function ($line) {
         if (preg_match('!^//.*$!', $line)) {
             return null;
@@ -55,10 +56,19 @@ function php_strip_whitespace($file): string
         return true;
     });
 
-    $lines = implode(" ", $tokens);
+    $text = implode(" ", $tokens);
+    $text = preg_replace('/\s\s+/', ' ', $text);
 
+    // Restore compatibility for heredoc blocks
+    // NOTE: Line-breaks inside heredoc are not preserved
+    preg_match("/.*<<<" . "'([A-Z]+)'/", $text, $m);
+    for ($i = 1; $i < count($m); $i++) {
+        $boundary = $m[$i];
+        $text = str_replace("<<<'$boundary'", "<<<'$boundary'\n", $text);
+        $text = str_replace("$boundary;", "\n$boundary;\n", $text);
+    }
 
-    return preg_replace('/\s\s+/', ' ', $lines);
+    return $text;
 }
 
 class Phar extends BuiltinPhar