diff --git a/boards/posix/nrf_bsim/Kconfig.defconfig b/boards/posix/nrf_bsim/Kconfig.defconfig
index 6993048248c..e762a3c6c85 100644
--- a/boards/posix/nrf_bsim/Kconfig.defconfig
+++ b/boards/posix/nrf_bsim/Kconfig.defconfig
@@ -44,7 +44,8 @@ config BT_CTLR
 	default y if BOARD_NRF52_BSIM || BOARD_NRF5340BSIM_NRF5340_CPUNET
 	depends on BT
 
-config HEAP_MEM_POOL_SIZE
+config HEAP_MEM_POOL_ADD_SIZE_BOARD
+	int
 	default 4096 if BT_HCI_IPC
 	default 4096 if NRF_802154_SER_HOST && BOARD_NRF5340BSIM_NRF5340_CPUAPP
 	default 4096 if NRF_802154_SER_RADIO && BOARD_NRF5340BSIM_NRF5340_CPUNET