diff --git a/include/ucore/rbtree.h b/include/ucore/rbtree.h
index bde88ef..edc271d 100644
--- a/include/ucore/rbtree.h
+++ b/include/ucore/rbtree.h
@@ -23,7 +23,7 @@ struct RBNode {
 typedef struct RBTree RBTree;
 struct RBTree {
 	RBNode *node;
-	int (*compare)(const void *a, const void *b);
+	int (*compare)(const RBNode *a, const RBNode *b);
 };
 
 /** Remove a node from the tree.
@@ -35,14 +35,16 @@ void uc_rb_remove(RBTree *root, RBNode *node);
 
 /** Find a node in the tree.
  *
- * The value to find will be in a node->data pointer, the compare
+ * The value to find must be of the same type as the
+ * other nodes inserted into a tree. This will normally
+ * be a user defined struct with the RBNode as one of its members
  * function of the tree is used to find the matching item.
  *
  * @param root Root of the tree
  * @param val The value to find.
  * @return the found node
  */
-RBNode *uc_rb_find(RBTree *root, const void *val);
+RBNode *uc_rb_find(RBTree *root, const RBNode *val);
 
 /** insert a new node
  *
diff --git a/src/rbtree.c b/src/rbtree.c
index 5522e4d..ebd1b71 100644
--- a/src/rbtree.c
+++ b/src/rbtree.c
@@ -251,11 +251,11 @@ uc_rb_remove(RBTree *root, RBNode *node)
 }
 
 RBNode*
-uc_rb_find(RBTree *root, const void *val)
+uc_rb_find(RBTree *root, const RBNode *val)
 {
 	RBNode *n = root->node;
 	while (n) {
-		int d = root->compare(val,n->data);
+		int d = root->compare(val,n);
 		if (d < 0)
 			n = n->left;
 		else if (d > 0)
@@ -274,7 +274,7 @@ uc_rb_insert(RBTree *root, RBNode *child)
 	int d;
 	while (*p) {
 		parent = *p;
-		d = root->compare(child->data, parent->data);
+		d = root->compare(child, parent);
 		if (d < 0)
 			p = &(*p)->left;
 		else if (d > 0)
diff --git a/src/timers.c b/src/timers.c
index 0aca525..b89381b 100644
--- a/src/timers.c
+++ b/src/timers.c
@@ -1,12 +1,13 @@
 #include <assert.h>
 #include "ucore/timers.h"
 #include "ucore/clock.h"
+#include "ucore/utils.h"
 
 
-static int timers_cmp(const void *a_, const void *b_)
+static int timers_cmp(const RBNode *a_, const RBNode *b_)
 {
-    const struct UCTimer *a = a_;
-    const struct UCTimer *b = b_;
+    const struct UCTimer *a = CONST_CONTAINER_OF(a_, struct UCTimer, rb_node);
+    const struct UCTimer *b = CONST_CONTAINER_OF(b_,  struct UCTimer, rb_node);
 
     if (timercmp(&a->timeout, &b->timeout, <)) {
         return -1;