--- org/apache/el/lang/ExpressionBuilder.java	(revision 607569)
+++ org/apache/el/lang/ExpressionBuilder.java	(working copy)
@@ -172,7 +172,7 @@ 
 						"error.fnMapper.method", funcNode.getOutputName()));
 			}
 			int pcnt = m.getParameterTypes().length;
-			if (node.jjtGetNumChildren() != pcnt) {
+			if (m.isVarArgs() ? pcnt - 1 > node.jjtGetNumChildren() : node.jjtGetNumChildren() != pcnt ) {
 				throw new ELException(MessageFactory.get(
 						"error.fnMapper.paramcount", funcNode.getOutputName(),
 						"" + pcnt, "" + node.jjtGetNumChildren()));