diff --git a/NEWS b/NEWS
index 5c255be4..4ab91637 100644
--- a/NEWS
+++ b/NEWS
@@ -1,3 +1,4 @@
+    - treat undefined constants as null (Ferdinand Beyer, Monte)
     - fix problem with inserts and nested fetches
       (Rainer Collet, Monte)
     - added support for passing params to include_php
diff --git a/Smarty_Compiler.class.php b/Smarty_Compiler.class.php
index 4ceb2f00..76e172bf 100644
--- a/Smarty_Compiler.class.php
+++ b/Smarty_Compiler.class.php
@@ -1774,10 +1774,7 @@ class Smarty_Compiler extends Smarty {
 
 			case 'const':
                 array_shift($indexes);
-				if(!defined(substr($indexes[0],1))) {
-                    $this->_syntax_error('$smarty' . implode('', $indexes) .' is an undefined constant', E_USER_ERROR, __FILE__, __LINE__);
-				}
-                $compiled_ref = substr($indexes[0],1);
+				$compiled_ref = 'defined(' . substr($indexes[0],1) . ') ? ' . substr($indexes[0],1) . ' : null';
                 break;
 
             default:
diff --git a/libs/Smarty_Compiler.class.php b/libs/Smarty_Compiler.class.php
index 4ceb2f00..76e172bf 100644
--- a/libs/Smarty_Compiler.class.php
+++ b/libs/Smarty_Compiler.class.php
@@ -1774,10 +1774,7 @@ class Smarty_Compiler extends Smarty {
 
 			case 'const':
                 array_shift($indexes);
-				if(!defined(substr($indexes[0],1))) {
-                    $this->_syntax_error('$smarty' . implode('', $indexes) .' is an undefined constant', E_USER_ERROR, __FILE__, __LINE__);
-				}
-                $compiled_ref = substr($indexes[0],1);
+				$compiled_ref = 'defined(' . substr($indexes[0],1) . ') ? ' . substr($indexes[0],1) . ' : null';
                 break;
 
             default: