Embodiments are directed towards generating applications that include multi-sized types running in managed code. During the compilation of an intermediate language version of an application, if a multi-size type is encountered, a runtime engine may perform actions to process the multi-size types. Accordingly, architecture information associated with the target computer may be determined. Data types corresponding to the architecture of the target computer and the multi-sized types may be determined based on the architecture information. Native code calls associated with an intermediate language code calls may be determined such that the parameters of the native code calls match the architecture dependent data types. And, a machine code version of the intermediate language code call may be generated. The generated machine code version of the intermediate language code may be executed with the data types specific to the target computer.