diff --git a/net/ipv4/fib_trie.c b/net/ipv4/fib_trie.c
index fcfa982..44cab1d 100644
--- a/net/ipv4/fib_trie.c
+++ b/net/ipv4/fib_trie.c
@@ -1530,7 +1530,7 @@
 	do {
 		/* record parent and next child index */
 		pn = n;
-		cindex = get_index(key, pn);
+		cindex = key ? get_index(key, pn) : 0;
 
 		if (cindex >> pn->bits)
 			break;