diff --git a/docs/technical/rbtree.txt b/docs/technical/rbtree.txt
index 36685a4..9d22f55 100644
--- a/docs/technical/rbtree.txt
+++ b/docs/technical/rbtree.txt
@@ -39,8 +39,7 @@ Functions
 `rbtree_insert()`::
 
     Creates and inserts a new node in the tree. +
-    If provided, calls `rbtree->delete_fn` if a node should be updated. +
-    Returns nonzero if a new node was inserted or updated, zero otherwise.
+    Returns a positive value if the node was inserted, zero if the key already exists in the tree and a negative value if an error occured.
 
 NOTE: The memory pointed to by the 'key' pointer is *not* copied so you must ensure that it has a infinite lifetime.
 
diff --git a/src/rbtree.c b/src/rbtree.c
index 4634662..f2acb2c 100644
--- a/src/rbtree.c
+++ b/src/rbtree.c
@@ -211,10 +211,10 @@ int rbtree_insert(rbtree *tree, const void *key) {
 	int dir = 0, last = 0;
 
     if (!tree || !tree->cmp_fn)
-        return 0;
+        return -1;
 
 	if (!tree->root) {
-		tree->root = node_alloc(key);
+		tree->root = q = node_alloc(key);
         goto done;
 	}
 		
@@ -259,12 +259,6 @@ int rbtree_insert(rbtree *tree, const void *key) {
 		q = q->child[dir];
 	}
 
-    if (q->key != key) {
-        if (tree->delete_fn)
-            tree->delete_fn((void*)q->key);
-        q->key = key;
-    }
-
 	tree->root = head.child[1];
 
 done:
@@ -275,7 +269,7 @@ done:
     rb_assert(tree);
 #endif
 
-    return 1;
+    return q && q->key == key;
 }
 
 void* rbtree_delete(rbtree *tree, const void *key) {