diff --git a/lib/bootconfig.c b/lib/bootconfig.c
index 2321cd0043c5..c2212d1a1acb 100644
--- a/lib/bootconfig.c
+++ b/lib/bootconfig.c
@@ -250,7 +250,7 @@ int __init xbc_node_compose_key_after(struct xbc_node *root,
 			       depth ? "." : "");
 		if (ret < 0)
 			return ret;
-		if (ret > size) {
+		if (ret >= size) {
 			size = 0;
 		} else {
 			size -= ret;