diff --git a/bsp/stm32f411-nucleo/Libraries/CMSIS/SConscript b/bsp/stm32f411-nucleo/Libraries/CMSIS/SConscript
index c54d81671646a50efd03fda29287819956019398..7425889371fcd6759ababf84e77c7bd495ffc9fe 100644
--- a/bsp/stm32f411-nucleo/Libraries/CMSIS/SConscript
+++ b/bsp/stm32f411-nucleo/Libraries/CMSIS/SConscript
@@ -18,7 +18,7 @@ elif rtconfig.CROSS_TOOL == 'keil':
 elif rtconfig.CROSS_TOOL == 'iar':
      folder = 'iar'
 #Device/ST/STM32F4xx/Source/Templates/iar/startup_stm32f411xe.s     
-src += ['Device/ST/STM32F4xx/Source/Templates/' + folder + '/startup_' + rtconfig.PART_TYPE+ '.s']
+src += ['Device/ST/STM32F4xx/Source/Templates/' + folder + '/startup_' + rtconfig.PART_TYPE.lower() + '.s']
 
 group = DefineGroup('CMSIS', src, depend = [''], CPPPATH = CPPPATH, CPPDEFINES = CPPDEFINES)