diff --git a/board/xilinx/versal/board.c b/board/xilinx/versal/board.c
index 8ea9eee..f0ac3fb 100644
--- a/board/xilinx/versal/board.c
+++ b/board/xilinx/versal/board.c
@@ -406,7 +406,7 @@
 
 	ALLOC_CACHE_ALIGN_BUFFER(char, buf, DFU_ALT_BUF_LEN);
 
-	memset(buf, 0, sizeof(buf));
+	memset(buf, 0, DFU_ALT_BUF_LEN);
 
 	multiboot = env_get_hex("multiboot", multiboot);