Update _lock.h in the rts source folder, rename the library you are using, and it will automatically be rebuilt during next compile. To find compiler install location, click on project properties and click on:    Resource->Linked Resources The "Path Variable" will have an entry for:    CG_TOOL_ROOT c:\install_location\ccsv6\tools\compiler\msp430_4.3.4 Within above folder look for:    .\lib\src\_lock.h    .\include\_lock.h Edit both of above files and change below line 47:  _CODE_ACCESS void _nop(void); to remove void argument and instead be:  _CODE_ACCESS void _nop(); Rename the library you are using with suffix .old:  .\lib\rtsx_lc_sd_eabi.lib change to a temp name  .\lib\rtsx_lc_sd_eabi.lib.old Rebuild your project and the rts should automatically rebuild.