diff --git a/meta-arm-bsp/recipes-security/trusted-services/corstone1000/0018-Change-RSS_COMMS-cmake-variables-to-cahce-vars.patch b/meta-arm-bsp/recipes-security/trusted-services/corstone1000/0018-Change-RSS_COMMS-cmake-variables-to-cahce-vars.patch
new file mode 100644
index 00000000..76e78fa3
--- /dev/null
+++ b/meta-arm-bsp/recipes-security/trusted-services/corstone1000/0018-Change-RSS_COMMS-cmake-variables-to-cahce-vars.patch
@@ -0,0 +1,37 @@
+From e8b577d02d1d4ed2492bb0b6c3a5bb7d2656f13a Mon Sep 17 00:00:00 2001
+From: Bence Balogh <bence.balogh@arm.com>
+Date: Fri, 17 May 2024 13:21:07 +0200
+Subject: [PATCH] Change RSS_COMMS cmake variables to cahce vars
+
+This way they can be set externally as well for the corstone1000
+platform.
+
+Signed-off-by: Bence Balogh <bence.balogh@arm.com>
+Upstream-Status: Pending
+---
+ platform/providers/arm/corstone1000/platform.cmake | 6 ++++--
+ 1 file changed, 4 insertions(+), 2 deletions(-)
+
+diff --git a/platform/providers/arm/corstone1000/platform.cmake b/platform/providers/arm/corstone1000/platform.cmake
+index 16139c80e..82ac14f0b 100644
+--- a/platform/providers/arm/corstone1000/platform.cmake
++++ b/platform/providers/arm/corstone1000/platform.cmake
+@@ -9,11 +9,13 @@
+ set(SMM_GATEWAY_MAX_UEFI_VARIABLES 80 CACHE STRING "Maximum UEFI variable count")
+ set(SMM_RPC_CALLER_SESSION_SHARED_MEMORY_SIZE 4*4096 CACHE STRING "RPC caller buffer size in SMMGW")
+ set(SMM_SP_HEAP_SIZE 80*1024 CACHE STRING "SMM gateway SP heap size")
++set(PLAT_RSS_COMMS_PAYLOAD_MAX_SIZE 0x43C0 CACHE STRING "Size of the RSS_COMMS_PAYLOAD buffer")
++set(COMMS_MHU_MSG_SIZE 0x4500 CACHE STRING "Max message size that can be transfered via MHU")
+ 
+ target_compile_definitions(${TGT} PRIVATE
+ 	SMM_VARIABLE_INDEX_STORAGE_UID=0x787
+-	PLAT_RSS_COMMS_PAYLOAD_MAX_SIZE=0x2080
+-	COMMS_MHU_MSG_SIZE=0x3500
++	PLAT_RSS_COMMS_PAYLOAD_MAX_SIZE=${PLAT_RSS_COMMS_PAYLOAD_MAX_SIZE}
++	COMMS_MHU_MSG_SIZE=${COMMS_MHU_MSG_SIZE}
+ )
+ 
+ get_property(_platform_driver_dependencies TARGET ${TGT}
+-- 
+2.25.1
+
diff --git a/meta-arm-bsp/recipes-security/trusted-services/ts-arm-platforms.inc b/meta-arm-bsp/recipes-security/trusted-services/ts-arm-platforms.inc
index 84c40aa8..837f6871 100644
--- a/meta-arm-bsp/recipes-security/trusted-services/ts-arm-platforms.inc
+++ b/meta-arm-bsp/recipes-security/trusted-services/ts-arm-platforms.inc
@@ -19,6 +19,7 @@ SRC_URI:append:corstone1000  = " \
     file://0015-Add-timestamp-validation-for-uefi-variables.patch \
     file://0016-Isolate-common-uefi-variable-authentication-steps.patch \
     file://0017-Implement-Private-Authenticated-Variable-verificatio.patch \
+    file://0018-Change-RSS_COMMS-cmake-variables-to-cahce-vars.patch \
     "
 
 COMPATIBLE_MACHINE:fvp-base = "fvp-base"
diff --git a/meta-arm-bsp/recipes-security/trusted-services/ts-sp-se-proxy_%.bbappend b/meta-arm-bsp/recipes-security/trusted-services/ts-sp-se-proxy_%.bbappend
index 31e4ea55..64ab5bea 100644
--- a/meta-arm-bsp/recipes-security/trusted-services/ts-sp-se-proxy_%.bbappend
+++ b/meta-arm-bsp/recipes-security/trusted-services/ts-sp-se-proxy_%.bbappend
@@ -2,6 +2,7 @@ require ts-arm-platforms.inc
 
 EXTRA_OECMAKE:append:corstone1000 = " -DMM_COMM_BUFFER_ADDRESS="0x00000000 0x81FFF000" \
     -DMM_COMM_BUFFER_PAGE_COUNT="1" \
+    -DSP_HEAP_SIZE=70*1024 \
     "
 
 # Proxy is pointless on fvp-base as there is no dedicated security subsystem. It could be