Eclipse: Problems View: Warnings: Eclipse Not Seeing JSTL libraries

Eclipse: Problems View: Warnings: Eclipse Not Seeing JSTL libraries

I'm using Eclpise 3.72 on Windows 7, with a legacy webapp.
In "Problems View" I am getting a lot of warnings about JSTL tags being
unknown, like this one:
Unknown tag (c:if)
Everything in the webapp compiles and runs beautifully.
I have the JSTL jars in my war/WEB-INF/lib
I have these tags in my header.jsp:
<%@ page language = "java" session = "true" import = "java.util.*,
java.text.*" %>
<%@ taglib prefix = "c" uri = "http://java.sun.com/jsp/jstl/core"%>
<%@ taglib prefix = "f" uri="http://www.springframework.org/tags/form"%>
I'm guessing Eclipse thinks those tags are unknown, because they are only
in the header.jsp which is included at the top of the other JSPs.
Is there anyway to get rid of those "unknown tag warnings" without
shutting off the JSP warnings?
Thanks.