diff --git a/recipes-security/optee/optee-os-stm32mp-common.inc b/recipes-security/optee/optee-os-stm32mp-common.inc
index 8cfbdd5..b108612 100644
--- a/recipes-security/optee/optee-os-stm32mp-common.inc
+++ b/recipes-security/optee/optee-os-stm32mp-common.inc
@@ -43,7 +43,8 @@ do_configure:prepend(){
 }
 
 do_compile() {
-    unset -v CFLAGS CPPFLAGS LDFLAGS LDADD
+    export CFLAGS="${CFLAGS} --sysroot=${STAGING_DIR_HOST}"
+    export OPENSSL_MODULES=${STAGING_LIBDIR_NATIVE}/ossl-modules/
     if [ -n "${OPTEE_CONF}" ]; then
         for conf in ${OPTEE_CONF}; do
             for soc in ${STM32MP_SOC_NAME}; do