The platform-agnostic nature of Java is made possible thanks to the presence ofthe Java Virtual Machine (JVM) with a well defined set of bytecodes and libraryroutines. This requires the availability of a JVM for many different platforms,32-bit as well as 64-bit wide. During an effort to port the Jikes ResearchVirtual Machine (RVM) to the64-bit PowerPC, we stumbled into a number of problems that prove that the Javaspecification was designed with a 32-bit platform in mind and that prevent anefficient implementation on a 64-bit platform. All described problems boil downto the fact that all types have a fixed size, while it is in the nature of some typesto automatically adapt to the word-size of the current platform.We would like toshare those issues with the community, so that future SPEC designerscan take into account these flaws. While Java declares to be platformindependent, we believe some aspects of the Java SPEC aredesigned too specific for a 32-bit platform.