diff --git a/src/util.c b/src/util.c
index 73d9a08..76c9452 100644
--- a/src/util.c
+++ b/src/util.c
@@ -1,5 +1,7 @@
 #include "util.h"
 #include "wm.h"
+#include <json-c/json_object.h>
+#include <json-c/json_tokener.h>
 #include <stdlib.h>
 #include <stdio.h>
 #include <string.h>
@@ -119,19 +121,39 @@ void wm_node_type_to_str(NodeType type, char *buf, size_t bufsize)
     }
 }
 
-void wm_treenode_to_str(TreeNode *node, char *buf, size_t bufsize)
+char* wm_treenode_to_str(TreeNode *node)
 {
     assert(node);
-    assert(buf);
     char type[128] = {0};
     wm_node_type_to_str(node->type, type, sizeof(type));
 
-    snprintf(buf, bufsize, "{ type: %s, parent: %p, children: { nodes: %p, "
-            "size: %ld, capacity: %ld }, pos: { x: %d, y: %d, w: %d, h: %d }, "
-            "client: %p, id: %d }\n", type, node->parent,
-            node->children.nodes, node->children.size, node->children.capacity,
-            node->pos.x, node->pos.y, node->pos.w, node->pos.h,
-            node->client, node->id);
+    json_object *jobj = json_object_new_object();
+
+    json_object_object_add(jobj, "type", json_object_new_string(type));
+    json_object_object_add(jobj, "parent", json_object_new_uint64((uint64_t)node->parent));
+    json_object_object_add(jobj, "children", json_object_new_array());
+
+    for (size_t i = 0; i < node->children.size; i++) {
+        char *child_str = wm_treenode_to_str(node->children.nodes[i]);
+        json_object_array_add(json_object_object_get(jobj, "children"),
+            json_tokener_parse(child_str));
+        free(child_str);
+    }
+
+    json_object *pos = json_object_new_object();
+    json_object_object_add(pos, "x", json_object_new_int(node->pos.x));
+    json_object_object_add(pos, "y", json_object_new_int(node->pos.y));
+    json_object_object_add(pos, "w", json_object_new_int(node->pos.w));
+    json_object_object_add(pos, "h", json_object_new_int(node->pos.h));
+    json_object_object_add(jobj, "pos", pos);
+    json_object_object_add(jobj, "client", json_object_new_uint64((uint64_t)node->client));
+    json_object_object_add(jobj, "id", json_object_new_uint64((uint64_t)node->id));
+
+
+    char *ret = strdup(json_object_to_json_string(jobj));
+    json_object_put(jobj);
+
+    return ret;
 }
 
 void wm_tree_to_DOT(TreeNode *root, const char *filename)
diff --git a/src/util.h b/src/util.h
index c9a3a93..5d81eae 100644
--- a/src/util.h
+++ b/src/util.h
@@ -4,6 +4,7 @@
 #include <stdbool.h>
 #include <stdlib.h>
 #include <string.h>
+#include <json-c/json.h>
 
 #include "client.h"
 
@@ -71,7 +72,7 @@ void wm_treenode_remove_node(TreeNode *root, unsigned int node_id);
 int wm_get_node_index(TreeNode *parent, unsigned int node_id);
 void wm_tree_to_DOT(TreeNode *root, const char *filename);
 void wm_node_type_to_str(NodeType type, char *buf, size_t bufsize);
-void wm_treenode_to_str(TreeNode *node, char *buf, size_t bufsize);
+char* wm_treenode_to_str(TreeNode *node);
 
 NodeArray wm_nodearray_new();
 void wm_nodearray_push(NodeArray *arr, TreeNode *node);