diff --git a/libfdt/fdt_rw.c b/libfdt/fdt_rw.c
index 85b6281..ff74e3c 100644
--- a/libfdt/fdt_rw.c
+++ b/libfdt/fdt_rw.c
@@ -329,6 +329,8 @@
 {
 	int endoffset;
 
+	RW_CHECK_HEADER(fdt);
+
 	endoffset = _fdt_node_end_offset(fdt, nodeoffset);
 	if (endoffset < 0)
 		return endoffset;