diff --git a/bsp/stm32f40x/rtconfig.py b/bsp/stm32f40x/rtconfig.py
index d1f081370e97c84077510ba7481d147b640c7642..3438597ee6a578e8c54967486e3155a58ba4be75 100644
--- a/bsp/stm32f40x/rtconfig.py
+++ b/bsp/stm32f40x/rtconfig.py
@@ -64,7 +64,7 @@ elif PLATFORM == 'armcc':
     LINK = 'armlink'
     TARGET_EXT = 'axf'
 
-    DEVICE = ' --cortex-m4.fp'
+    DEVICE = ' --cpu=cortex-m4.fp'
     CFLAGS = DEVICE + ' --apcs=interwork -DUSE_STDPERIPH_DRIVER -DSTM32F40_41xxx'
     AFLAGS = DEVICE
     LFLAGS = DEVICE + ' --info sizes --info totals --info unused --info veneers --list rtthread-stm32.map --scatter stm32_rom.sct'