diff --git a/src/tree.c b/src/tree.c
index b6a3e15..f921a90 100644
--- a/src/tree.c
+++ b/src/tree.c
@@ -26,18 +26,11 @@ void tree_node_init(tree_node_t* node) {
 int tree_add(tree_t* tree, tree_node_t* node, uintptr_t key) {
   tree_node_t* existing_node;
 
-  if (key == 0)
-    return_error(-1, ERROR_INVALID_PARAMETER);
-  if (node->key != 0)
-    return_error(-1, ERROR_ALREADY_EXISTS);
-
   node->key = key;
   existing_node = RB_INSERT(tree, tree, node);
 
-  if (existing_node != NULL) {
-    node->key = 0;
+  if (existing_node != NULL)
     return_error(-1, ERROR_ALREADY_EXISTS);
-  }
 
   return 0;
 }
@@ -45,9 +38,6 @@ int tree_add(tree_t* tree, tree_node_t* node, uintptr_t key) {
 int tree_del(tree_t* tree, tree_node_t* node) {
   tree_node_t* removed_node;
 
-  if (node->key == 0)
-    return_error(-1, ERROR_NOT_FOUND);
-
   removed_node = RB_REMOVE(tree, tree, node);
 
   if (removed_node == NULL)
@@ -55,8 +45,6 @@ int tree_del(tree_t* tree, tree_node_t* node) {
   else
     assert(removed_node == node);
 
-  node->key = 0;
-
   return 0;
 }
 
@@ -64,9 +52,6 @@ tree_node_t* tree_find(tree_t* tree, uintptr_t key) {
   tree_node_t* node;
   tree_node_t lookup;
 
-  if (key == 0)
-    return_error(NULL, ERROR_INVALID_PARAMETER);
-
   memset(&lookup, 0, sizeof lookup);
   lookup.key = key;