There are 2 parts to this bug. 1) The compiler makes an infinite loop by calling self.set_Property(value) instead of super.set_Property(value) in the overridden property setter. See thread http://groups.google.com/group/boolang/browse_thread/thread/f946fad0ac453351 for more information. 2) Compilation fails if the class (or another class) attempts to set the property on an earlier line than the property declaration. See thread See thread http://groups.google.com/group/boolang/browse_thread/thread/5136634864640ea7 for more information. Here is a test case: class A: virtual Kaboom: get: return true set: pass class B(A): //comment out this method to allow compilation and reveal the infinite loop bug private def CompileKaboom(): self.Kaboom = true override Kaboom: get: return super.Kaboom set: super.Kaboom = value