java.lang.ClassFormatError when running in Java 1.5

When attempting to run Cactus in Java 1.5, I get the following error:

(this is inside of JBoss 3.2.4, but I've seen the exact same error when running from the command line)

java.lang.ClassFormatError: Invalid index 0 in LocalVariableTable in class file org/apache/cactus/util/log/LogAspect
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClass(ClassLoader.java:605)
at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:124)
at org.apache.catalina.loader.WebappClassLoader.findClassInternal(WebappClassLoader.java:1634)
at org.apache.catalina.loader.WebappClassLoader.findClass(WebappClassLoader.java:860)
at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1307)
at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1189)
at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:303)
at org.apache.cactus.server.FilterTestRedirector.init(FilterTestRedirector.java)
at org.apache.catalina.core.ApplicationFilterConfig.getFilter(ApplicationFilterConfig.java:225)
at org.apache.catalina.core.ApplicationFilterConfig.setFilterDef(ApplicationFilterConfig.java:308)

So, I'm not sure if there needs to be a special version build just for 1.5, which would be unfortunate. Every other library I've used has been OK, so I'd suspect it's something with Aspecj's 'weaving'? (shrug)

Thanks for any assistance!