diff --git a/sys/net/radix.c b/sys/net/radix.c
index 39b198eaf49e..a494adf10c78 100644
--- a/sys/net/radix.c
+++ b/sys/net/radix.c
@@ -72,6 +72,8 @@ static struct radix_node_head *mask_rnhead;
 /*
  * Work area -- the following point to 3 buffers of size max_keylen,
  * allocated in this order in a block of memory malloc'ed by rn_init.
+ * rn_zeros, rn_ones are set in rn_init and used in readonly afterwards.
+ * addmask_key is used in rn_addmask in rw mode and not thread-safe.
  */
 static char *rn_zeros, *rn_ones, *addmask_key;
 
@@ -135,8 +137,9 @@ static int	rn_satisfies_leaf(char *trial, struct radix_node *leaf,
  * To make the assumption more explicit, we use the LEN() macro to access
  * this field. It is safe to pass an expression with side effects
  * to LEN() as the argument is evaluated only once.
+ * We cast the result to int as this is the dominant usage.
  */
-#define LEN(x) (*(const u_char *)(x))
+#define LEN(x) ( (int) (*(const u_char *)(x)) )
 
 /*
  * XXX THIS NEEDS TO BE FIXED
@@ -197,7 +200,7 @@ rn_refines(m_arg, n_arg)
 {
 	register caddr_t m = m_arg, n = n_arg;
 	register caddr_t lim, lim2 = lim = n + LEN(n);
-	int longer = LEN(n++) - (int)LEN(m++);
+	int longer = LEN(n++) - LEN(m++);
 	int masks_are_equal = 1;
 
 	if (longer > 0)
@@ -250,10 +253,10 @@ rn_satisfies_leaf(trial, leaf, skip)
 	char *cplim;
 	int length = min(LEN(cp), LEN(cp2));
 
-	if (cp3 == 0)
+	if (cp3 == NULL)
 		cp3 = rn_ones;
 	else
-		length = min(length, *(u_char *)cp3);
+		length = min(length, LEN(cp3));
 	cplim = cp + length; cp3 += skip; cp2 += skip;
 	for (cp += skip; cp < cplim; cp++, cp2++, cp3++)
 		if ((*cp ^ *cp2) & *cp3)
@@ -424,7 +427,7 @@ rn_insert(v_arg, head, dupentry, nodes)
 {
 	caddr_t v = v_arg;
 	struct radix_node *top = head->rnh_treetop;
-	int head_off = top->rn_offset, vlen = (int)LEN(v);
+	int head_off = top->rn_offset, vlen = LEN(v);
 	register struct radix_node *t = rn_search(v_arg, top);
 	register caddr_t cp = v + head_off;
 	register int b;