diff --git a/targets/TARGET_STM/TARGET_STM32F4/TARGET_STM32F429xI/device/TOOLCHAIN_IAR/stm32f429xx_flash.icf b/targets/TARGET_STM/TARGET_STM32F4/TARGET_STM32F429xI/device/TOOLCHAIN_IAR/stm32f429xx_flash.icf
index c2b9d0d7f8..94c7d061c0 100644
--- a/targets/TARGET_STM/TARGET_STM32F4/TARGET_STM32F429xI/device/TOOLCHAIN_IAR/stm32f429xx_flash.icf
+++ b/targets/TARGET_STM/TARGET_STM32F4/TARGET_STM32F429xI/device/TOOLCHAIN_IAR/stm32f429xx_flash.icf
@@ -15,9 +15,9 @@ define symbol __ICFEDIT_region_RAM_end__      = 0x2002FFFF;
 define symbol __ICFEDIT_region_CCMRAM_start__ = 0x10000000;
 define symbol __ICFEDIT_region_CCMRAM_end__   = 0x1000FFFF;
 /*-Sizes-*/
-/*Heap 1/2 of ram and stack 1/8*/
+/*Heap 64K and stack 24K */
 define symbol __ICFEDIT_size_cstack__ = 0x6000;
-define symbol __ICFEDIT_size_heap__   = 0x18000;
+define symbol __ICFEDIT_size_heap__   = 0x10000;
 /**** End of ICF editor section. ###ICF###*/
 
 
diff --git a/targets/TARGET_STM/TARGET_STM32F4/TARGET_UBLOX_EVK_ODIN_W2/device/TOOLCHAIN_IAR/stm32f439xx_flash.icf b/targets/TARGET_STM/TARGET_STM32F4/TARGET_UBLOX_EVK_ODIN_W2/device/TOOLCHAIN_IAR/stm32f439xx_flash.icf
index c2b9d0d7f8..9a41a3c0c5 100644
--- a/targets/TARGET_STM/TARGET_STM32F4/TARGET_UBLOX_EVK_ODIN_W2/device/TOOLCHAIN_IAR/stm32f439xx_flash.icf
+++ b/targets/TARGET_STM/TARGET_STM32F4/TARGET_UBLOX_EVK_ODIN_W2/device/TOOLCHAIN_IAR/stm32f439xx_flash.icf
@@ -15,9 +15,9 @@ define symbol __ICFEDIT_region_RAM_end__      = 0x2002FFFF;
 define symbol __ICFEDIT_region_CCMRAM_start__ = 0x10000000;
 define symbol __ICFEDIT_region_CCMRAM_end__   = 0x1000FFFF;
 /*-Sizes-*/
-/*Heap 1/2 of ram and stack 1/8*/
+/*Heap 64kB and stack 24kB */
 define symbol __ICFEDIT_size_cstack__ = 0x6000;
-define symbol __ICFEDIT_size_heap__   = 0x18000;
+define symbol __ICFEDIT_size_heap__   = 0x10000;
 /**** End of ICF editor section. ###ICF###*/