PMD exclusion property only accepts one exclusion

When trying to exclude files from PMD analysis, it seems that a single exclusion pattern works fine, but as soon as I put in a comma separated list all the exclusions are ignored. For example:

maven.pmd.includes=com/foo/project/*/.java
maven.pmd.excludes=com/foo/project/package/SomeParser*.java

works fine, analysing everything except the SomeParser classes. However,

maven.pmd.includes=com/foo/project/*/.java
maven.pmd.excludes=com/foo/project/package/SomeParser*.java, com/foo/project/package/ADifferentParser*.java

causes the analyser to match as though only maven.pmd.includes was specified.