diff --git a/a3/binary_search_tree.c b/a3/binary_search_tree.c
index 4cfa7af..b5c381f 100644
--- a/a3/binary_search_tree.c
+++ b/a3/binary_search_tree.c
@@ -58,18 +58,22 @@ int *sorted_data(node_t *tree) {
     return sorted_array;
 }
 
-node_t *build_tree(int *tree_data, size_t tree_data_len){
-
-    node_t *koren = (node_t *)malloc(sizeof(node_t));
-
-    if(tree_data == NULL || tree_data_len == 0){
-        return 0;
+node_t *build_tree(int *tree_data, size_t tree_data_len) {
+    if (tree_data == NULL || tree_data_len == 0) {
+        return NULL;
     }
 
-    if(tree_data != NULL && tree_data_len != 0){
-        koren->data = tree_data[0];
-        koren->left = (node_t *)malloc(sizeof(node_t));
-        koren->left->data = tree_data[0];
+    node_t *koren = (node_t *)malloc(sizeof(node_t));
+    if (koren == NULL) {
+        return NULL;
+    }
+
+    koren->data = tree_data[0];
+    koren->left = NULL;
+    koren->right = NULL;
+
+    if (tree_data_len > 1) {
+        koren->left = build_tree(tree_data + 1, tree_data_len - 1);
     }
 
     return koren;