diff --git a/3rd/cjson/src/cJSONw.cpp b/3rd/cjson/src/cJSONw.cpp
index 38b352ce..4b5fb712 100644
--- a/3rd/cjson/src/cJSONw.cpp
+++ b/3rd/cjson/src/cJSONw.cpp
@@ -127,7 +127,7 @@ void add_module_cjson(VM* vm){
 
         const Str& expr = CAST(Str&, args[0]);
 
-        cJSON *json = cJSON_Parse(expr.c_str());
+        cJSON *json = cJSON_ParseWithLength(expr.data, expr.size);
 
         PyObject* output = convert_cjson_to_python_object(json, vm);
         cJSON_Delete(json);
diff --git a/tests/80_json.py b/tests/80_json.py
index f6e467bb..17e09498 100644
--- a/tests/80_json.py
+++ b/tests/80_json.py
@@ -14,7 +14,11 @@ a = {
     'h': False
 }
 
-import cjson as json
+try:
+    import cjson as json
+    print('[INFO] cjson is used')
+except ImportError:
+    import json
 
 _j = json.dumps(a)
 _a = json.loads(_j)
diff --git a/tests/82_ldtk.py b/tests/82_ldtk.py
index bfb064b5..5d480955 100644
--- a/tests/82_ldtk.py
+++ b/tests/82_ldtk.py
@@ -1,4 +1,8 @@
-import cjson as json
+try:
+    import cjson as json
+    print('[INFO] cjson is used')
+except ImportError:
+    import json
 
 _2489KB = 'WorldMap_GridVania_layout.ldtk'
 _1093KB = 'WorldMap_Free_layout.ldtk'