diff --git a/components/libc/compilers/common/SConscript b/components/libc/compilers/common/SConscript
index 9c3229eb5d..cf57f2abc3 100644
--- a/components/libc/compilers/common/SConscript
+++ b/components/libc/compilers/common/SConscript
@@ -9,6 +9,8 @@ CPPDEFINES = []
 
 if rtconfig.PLATFORM in ['armcc', 'armclang']:
     CPPDEFINES += ['__CLK_TCK=RT_TICK_PER_SECOND']
+elif rtconfig.PLATFORM == 'iar':
+    CPPDEFINES += ['CLOCKS_PER_SEC=RT_TICK_PER_SECOND'] # forcly revert to 1 by IAR
 
 src += Glob('*.c')