diff --git a/src/builtin.cmod b/src/builtin.cmod
index e1be74c090755ad70bb74d37f4eefc5e04ad58be..08720fda1c418c68424d9de20aa03c7a9751b641 100644
--- a/src/builtin.cmod
+++ b/src/builtin.cmod
@@ -2,7 +2,7 @@
 || This file is part of Pike. For copyright information see COPYRIGHT.
 || Pike is distributed under GPL, LGPL and MPL. See the file COPYING
 || for more information.
-|| $Id: builtin.cmod,v 1.129 2003/04/07 15:30:10 mast Exp $
+|| $Id: builtin.cmod,v 1.130 2003/04/07 16:19:15 mast Exp $
 */
 
 #include "global.h"
@@ -1694,6 +1694,12 @@ PIKECLASS Buffer
     RETURN res;
   }
 
+  PIKEFUN object `+=( string what )
+  {
+    f_Buffer_add( 1 );
+    REF_RETURN Pike_fp->current_object;
+  }
+
   /*! @decl int add(string ... data)
    *!
    *!   Adds @[data] to the buffer. Returns the size of the buffer.