diff --git a/mk.bat b/mk.bat
index 367c0f1..a0b52b7 100644
--- a/mk.bat
+++ b/mk.bat
@@ -1,8 +1,8 @@
 @REM D:\Lang\cmake-3.27.5-windows-x86_64\bin\cmake.EXE --no-warn-unused-cli -DCMAKE_BUILD_TYPE:STRING=Debug -DCMAKE_EXPORT_COMPILE_COMMANDS:BOOL=TRUE -DCMAKE_C_COMPILER:FILEPATH=D:\Software\mingw64\bin\gcc.exe -DCMAKE_CXX_COMPILER:FILEPATH=D:\Software\mingw64\bin\g++.exe -SF:/OpenDemo/1_vsc_cmake -Bf:/OpenDemo/1_vsc_cmake/build -G "MinGW Makefiles"
 @REM cmake -Bbuild -G "Visual Studio 17 2022"
 
-@REM cmake -B build -G "MinGW Makefiles"
-cmake -B build -G "Unix Makefiles"
+cmake -B build -G "MinGW Makefiles"
+@REM cmake -B build -G "Unix Makefiles"
 
 make -C build
 make -C build install 
diff --git a/src/tree.c b/src/tree.c
index ec04664..55f1ac4 100644
--- a/src/tree.c
+++ b/src/tree.c
@@ -1541,7 +1541,8 @@ static bool tree_avl_rebalance(struct _tree* self, struct _tree_node* root)
     {
         return true;
     }
-    self->print_obj(root->obj);
+
+    // self->print_obj(root->obj);
     tree_set_balance(self, root);
     int balance = root->balance;
     if(balance == 2)
@@ -1778,12 +1779,16 @@ static bool tree_avl_delete_double_child(struct _tree* self, struct _tree_node*
     assert(self != NULL);
     assert(node != NULL);
     struct _tree_node* tmp = self->find_min(self, node->right);
-    if(tmp == NULL)
+    if(tmp != NULL)
     {
-        return false;
+        memmove(node->obj, tmp->obj, self->_obj_size);
+        if(tmp->right != NULL)
+        {
+            node->right = tmp->right;
+            tmp->right->parent = node;
+        }
+        tree_avl_delete_single_child(self, tmp);
     }
-    memmove(node->obj, tmp->obj, self->_obj_size);
-    tree_avl_delete_single_child(self, tmp);
     return true;
 }
 
@@ -1803,6 +1808,8 @@ bool tree_avl_delete(struct _tree* self, void* obj)
     {
         return false;
     }
+    // debug
+    self->print_obj(obj);
 
     if(node->left != NULL && node->right != NULL)
     {
diff --git a/test/test_tree.c b/test/test_tree.c
index 5af58ce..1fb081b 100644
--- a/test/test_tree.c
+++ b/test/test_tree.c
@@ -298,9 +298,9 @@ void test_tree_num(void)
     {
         tree->insert(tree, &data[i]);
 
-        printf("----- preorder -----\n");
-        tree->preorder(tree, tree->_root);
-        printf("\n");
+        // printf("----- preorder -----\n");
+        // tree->preorder(tree, tree->_root);
+        // printf("\n");
     }
     printf("----- preorder -----\n");
     tree->preorder(tree, tree->_root);
@@ -355,10 +355,10 @@ void test_tree_num(void)
 
         tree->delete(tree, &temp);
 
-        printf("----- breadth -----\n");
-        tree->breadth(tree, tree->_root);
-        printf("----- inorder -----\n");
-        tree->inorder(tree, tree->_root);
+        // printf("----- breadth -----\n");
+        // tree->breadth(tree, tree->_root);
+        printf("----- preorder -----\n");
+        tree->preorder(tree, tree->_root);
         printf("\n");
     }