diff --git a/hmap.c b/hmap.c
index 4a7a714..f3763db 100644
--- a/hmap.c
+++ b/hmap.c
@@ -55,9 +55,9 @@ uint64_t hash_fnv1a_64(uint8_t *key, size_t len) {
 }
 
 struct _map_node {
-    struct _map_node *lt;
-    struct _map_node *gt;
-    uint64_t key;
+    struct _map_node *next;
+    void * key;
+    uint64_t hash;
     void *data;
 };
 
@@ -76,11 +76,31 @@ hmap_node* hmap_node_init(void *key, size_t keysize, void *data) {
     hash = hash_fnv1a_64(key, keysize);
     node = calloc(1, sizeof(hmap_node));
     if (node == NULL) return NULL;
-    node->key = hash;
+    node->key = key;
+    node->hash = hash;
     node->data = data;
     return node;
 }
 
+void* hmap_node_attach(hmap_node *root, hmap_node *leaf) {
+    void *ret = NULL;
+
+    while (1) {
+        if (root->key == leaf->key) {
+            ret = root->data;
+            root->data = leaf->data;
+            return ret;
+        } else if (root->next == NULL) {
+            root->next = leaf;
+            break;
+        } else {
+            root = root->next;
+        }
+    }
+    return NULL;
+    // todo
+}
+
 hmap* hmap_init() {
     hmap* map;
 
@@ -96,10 +116,26 @@ hmap* hmap_init() {
     return map;
 }
 
+int hmap_expand(hmap *map) {
+    return 0;
+}
+
 hmap_node* hmap_insert(hmap * map, void *key, size_t keysize, void *data) {
     hmap_node *node;
+    size_t idx;
+    hmap_node *ret = NULL;
 
+    if (map->len >= map->capacity / 2) {
+        if (hmap_expand(map)) return NULL;
+    }
     node = hmap_node_init(key, keysize, data);
     if (node == NULL) return NULL;
+    idx = node->hash % map->capacity;
+    if (map->buckets[idx].key == NULL) {
+        map->buckets[idx] = *node;
+    } else {
+        ret = hmap_node_attach(&map->buckets[idx], node);
+    }
     // todo
+    return ret;
 }