diff --git a/lib/bootconfig.c b/lib/bootconfig.c
index 94ae6662531d..9f059bb68e41 100644
--- a/lib/bootconfig.c
+++ b/lib/bootconfig.c
@@ -195,7 +195,7 @@ static bool __init
 xbc_node_match_prefix(struct xbc_node *node, const char **prefix)
 {
 	const char *p = xbc_node_get_data(node);
-	int len = strlen(p);
+	size_t len = strlen(p);
 
 	if (strncmp(*prefix, p, len))
 		return false;