diff --git a/subsys/dfu/img_util/flash_img.c b/subsys/dfu/img_util/flash_img.c
index cc703ed6d4b..085cee589bd 100644
--- a/subsys/dfu/img_util/flash_img.c
+++ b/subsys/dfu/img_util/flash_img.c
@@ -23,6 +23,14 @@ LOG_MODULE_REGISTER(LOG_MODULE_NAME);
 #include <flash.h>
 #endif
 
+#include <generated_dts_board.h>
+/* DT_FLASH_AREA_IMAGE_XX_YY values used below are auto-generated by DT */
+#ifdef CONFIG_TRUSTED_EXECUTION_NONSECURE
+#define FLASH_AREA_IMAGE_SECONDARY DT_FLASH_AREA_IMAGE_1_NONSECURE_ID
+#else
+#define FLASH_AREA_IMAGE_SECONDARY DT_FLASH_AREA_IMAGE_1_ID
+#endif /* CONFIG_TRUSTED_EXECUTION_NONSECURE */
+
 BUILD_ASSERT_MSG((CONFIG_IMG_BLOCK_BUF_SIZE % DT_FLASH_WRITE_BLOCK_SIZE == 0),
 		 "CONFIG_IMG_BLOCK_BUF_SIZE is not a multiple of "
 		 "DT_FLASH_WRITE_BLOCK_SIZE");
@@ -212,6 +220,6 @@ int flash_img_init(struct flash_img_context *ctx)
 #ifdef CONFIG_IMG_ERASE_PROGRESSIVELY
 	ctx->off_last = -1;
 #endif
-	return flash_area_open(DT_FLASH_AREA_IMAGE_1_ID,
+	return flash_area_open(FLASH_AREA_IMAGE_SECONDARY,
 			       (const struct flash_area **)&(ctx->flash_area));
 }