diff --git a/secure_fw/spm/ffm/backend.c b/secure_fw/spm/ffm/backend.c
deleted file mode 100644
index 9df5de7..0000000
--- a/secure_fw/spm/ffm/backend.c
+++ /dev/null
@@ -1,15 +0,0 @@
-/*
- * Copyright (c) 2021, Arm Limited. All rights reserved.
- *
- * SPDX-License-Identifier: BSD-3-Clause
- *
- */
-#include "config_impl.h"
-
-#if CONFIG_TFM_SPM_BACKEND_SFN == 1
-#include "backend_sfn.c"
-#elif CONFIG_TFM_SPM_BACKEND_IPC == 1
-#include "backend_ipc.c"
-#else
-#error "Invalid configuration."
-#endif
diff --git a/secure_fw/spm/ffm/backend_ipc.c b/secure_fw/spm/ffm/backend_ipc.c
index 443c5da..543282a 100644
--- a/secure_fw/spm/ffm/backend_ipc.c
+++ b/secure_fw/spm/ffm/backend_ipc.c
@@ -23,7 +23,7 @@
 /* Declare the global component list */
 struct partition_head_t partition_listhead;
 
-#ifdef CONFIG_TFM_PSA_API_CROSS_CALL
+#if CONFIG_TFM_PSA_API_CROSS_CALL == 1
 
 #ifdef TFM_MULTI_CORE_TOPOLOGY
 /* TODO: To be checked when RPC design updates. */
@@ -115,7 +115,7 @@
     THRD_INIT(&p_pt->thrd, &p_pt->ctx_ctrl,
               TO_THREAD_PRIORITY(PARTITION_PRIORITY(p_pldi->flags)));
 
-#if defined(CONFIG_TFM_PSA_API_CROSS_CALL) && !defined(TFM_MULTI_CORE_TOPOLOGY)
+#if (CONFIG_TFM_PSA_API_CROSS_CALL == 1) && !defined(TFM_MULTI_CORE_TOPOLOGY)
     if (p_pldi->pid == TFM_SP_NON_SECURE_ID) {
         SPM_THREAD_CONTEXT = &p_pt->ctx_ctrl;
     }
@@ -132,7 +132,7 @@
     uint32_t control;
     struct partition_t *p_cur_pt;
 
-#ifdef CONFIG_TFM_PSA_API_THREAD_CALL
+#if CONFIG_TFM_PSA_API_THREAD_CALL == 1
     TFM_CORE_ASSERT(SPM_THREAD_CONTEXT);
 #endif