diff --git a/interface/include/config_impl.h.template b/interface/include/config_impl.h.template
index 4a172e3..ade895c 100644
--- a/interface/include/config_impl.h.template
+++ b/interface/include/config_impl.h.template
@@ -27,7 +27,7 @@
 
 #if CONFIG_TFM_SPM_BACKEND_IPC == 1
 /* Trustzone NS agent working stack size. */
-#if defined(TFM_FIH_PROFILE_ON) && TFM_LVL == 1
+#if defined(TFM_FIH_PROFILE_ON) && TFM_ISOLATION_LEVEL == 1
 #define {{"%-56s"|format("CONFIG_TFM_NS_AGENT_TZ_STACK_SIZE")}} 1256
 #else
 #define {{"%-56s"|format("CONFIG_TFM_NS_AGENT_TZ_STACK_SIZE")}} 1024