ConcurrentModificationException when trying to allocate node within EC2 cloud profile

Stack:
2015-04-14 09:48:00,916 [Thread-79] ERROR com.pmease.quickbuild.DefaultBuildEngine - Error allocating node for step 'master'.
 java.util.ConcurrentModificationException
        at java.util.LinkedHashMap$LinkedHashIterator.nextEntry(Unknown Source)
        at java.util.LinkedHashMap$EntryIterator.next(Unknown Source)
        at java.util.LinkedHashMap$EntryIterator.next(Unknown Source)
        at java.util.HashMap.putAllForCreate(Unknown Source)
        at java.util.HashMap.<init>(Unknown Source)
        at com.pmease.quickbuild.DefaultBuildEngine.findCloudProfile(DefaultBuildEngine.java:1283)
        at com.pmease.quickbuild.DefaultBuildEngine.run(DefaultBuildEngine.java:1167)
        at java.lang.Thread.run(Unknown Source)