diff --git a/targets/TARGET_NUVOTON/TARGET_NANO100/device/TOOLCHAIN_IAR/NANO130.icf b/targets/TARGET_NUVOTON/TARGET_NANO100/device/TOOLCHAIN_IAR/NANO130.icf
index 4cb16de2d3..1663174b16 100644
--- a/targets/TARGET_NUVOTON/TARGET_NANO100/device/TOOLCHAIN_IAR/NANO130.icf
+++ b/targets/TARGET_NUVOTON/TARGET_NANO100/device/TOOLCHAIN_IAR/NANO130.icf
@@ -10,7 +10,7 @@ define symbol __ICFEDIT_region_IRAM_start__ = 0x20000000;
 define symbol __ICFEDIT_region_IRAM_end__   = 0x20004000 - 1;
 /*-Sizes-*/
 define symbol __ICFEDIT_size_cstack__ = 0x600;
-define symbol __ICFEDIT_size_heap__   = 0x1200;
+define symbol __ICFEDIT_size_heap__   = 0x1000;
 /**** End of ICF editor section. ###ICF###*/