diff --git a/plat/st/stm32mp1/platform.mk b/plat/st/stm32mp1/platform.mk
index 127e318..a903a16 100644
--- a/plat/st/stm32mp1/platform.mk
+++ b/plat/st/stm32mp1/platform.mk
@@ -65,6 +65,10 @@
 # STM32 image header version v1.0
 STM32_HEADER_VERSION_MAJOR:=	1
 STM32_HEADER_VERSION_MINOR:=	0
+
+# Add OP-TEE reserved shared memory area in mapping
+STM32MP15_OPTEE_RSV_SHM	:=	1
+$(eval $(call add_defines,STM32MP15_OPTEE_RSV_SHM))
 endif
 
 # STM32 image header binary type for BL2