diff --git a/targets/TARGET_NXP/TARGET_MCUXpresso_MCUS/TARGET_LPC55S69/TARGET_M33_NS/device/TOOLCHAIN_IAR/LPC55S69_cm33_core0_flash.icf b/targets/TARGET_NXP/TARGET_MCUXpresso_MCUS/TARGET_LPC55S69/TARGET_M33_NS/device/TOOLCHAIN_IAR/LPC55S69_cm33_core0_flash.icf
index 85863bde4e..0034019b6d 100644
--- a/targets/TARGET_NXP/TARGET_MCUXpresso_MCUS/TARGET_LPC55S69/TARGET_M33_NS/device/TOOLCHAIN_IAR/LPC55S69_cm33_core0_flash.icf
+++ b/targets/TARGET_NXP/TARGET_MCUXpresso_MCUS/TARGET_LPC55S69/TARGET_M33_NS/device/TOOLCHAIN_IAR/LPC55S69_cm33_core0_flash.icf
@@ -126,7 +126,7 @@ define region CSTACK_region = mem:[from m_data_end-__size_cstack__+1 to m_data_e
 define region m_interrupts_ram_region = mem:[from m_interrupts_ram_start to m_interrupts_ram_end];
 
 define block CSTACK    with alignment = 8, size = __size_cstack__   { };
-define block HEAP      with alignment = 8, size = __size_heap__     { };
+define block HEAP      with expanding size, alignment = 8, minimum size = __heap_size__ { };
 define block RW        { readwrite };
 define block ZI        { zi };