diff --git a/3rd/cjson/CMakeLists.txt b/3rd/cjson/CMakeLists.txt
index 2cadd692..339b502b 100644
--- a/3rd/cjson/CMakeLists.txt
+++ b/3rd/cjson/CMakeLists.txt
@@ -2,14 +2,18 @@ cmake_minimum_required(VERSION 3.10)
 
 project(cjson)
 
+set(CMAKE_C_STANDARD 11)
 set(CMAKE_CXX_STANDARD 17)
 
 include_directories(${CMAKE_CURRENT_LIST_DIR}/include)
 include_directories(${CMAKE_CURRENT_LIST_DIR}/../pocketpy/include)
 
+set(CMAKE_C_FLAGS_RELEASE "-O2")
 set(CMAKE_CXX_FLAGS_RELEASE "-O2")
+set(CMAKE_POSITION_INDEPENDENT_CODE ON)
 
 add_library(
     cjson
-    ${CMAKE_CURRENT_LIST_DIR}/src/cJSON.cpp
+    ${CMAKE_CURRENT_LIST_DIR}/src/cJSON.c
+    ${CMAKE_CURRENT_LIST_DIR}/src/cJSONw.cpp
 )
diff --git a/3rd/cjson/include/cjson/cJSON.h b/3rd/cjson/include/cJSON.h
similarity index 100%
rename from 3rd/cjson/include/cjson/cJSON.h
rename to 3rd/cjson/include/cJSON.h
diff --git a/3rd/cjson/include/cJSONw.hpp b/3rd/cjson/include/cJSONw.hpp
new file mode 100644
index 00000000..856165be
--- /dev/null
+++ b/3rd/cjson/include/cJSONw.hpp
@@ -0,0 +1,8 @@
+#include "cJSON.h"
+#include "pocketpy/pocketpy.h"
+
+namespace pkpy {
+
+void add_module_cjson(VM* vm);
+
+}   // namespace pkpy
\ No newline at end of file
diff --git a/3rd/cjson/src/cJSON.cpp b/3rd/cjson/src/cJSON.c
similarity index 99%
rename from 3rd/cjson/src/cJSON.cpp
rename to 3rd/cjson/src/cJSON.c
index ce271649..f6dd11c5 100644
--- a/3rd/cjson/src/cJSON.cpp
+++ b/3rd/cjson/src/cJSON.c
@@ -56,7 +56,7 @@
 #pragma GCC visibility pop
 #endif
 
-#include "cjson.hpp"
+#include "cJSON.h"
 
 /* define our own boolean type */
 #ifdef true
diff --git a/3rd/cjson/include/cjson.hpp b/3rd/cjson/src/cJSONw.cpp
similarity index 97%
rename from 3rd/cjson/include/cjson.hpp
rename to 3rd/cjson/src/cJSONw.cpp
index 422ed7d0..b640eb6b 100644
--- a/3rd/cjson/include/cjson.hpp
+++ b/3rd/cjson/src/cJSONw.cpp
@@ -1,6 +1,4 @@
-#include "cjson/cJSON.h"
-#include "pocketpy/pocketpy.h"
-
+#include "cJSONw.hpp"
 
 namespace pkpy{
 
@@ -90,7 +88,7 @@ static Dict convert_cjson_to_dict(const cJSON * const item, VM* vm)
     return output;
 }
 
-inline void add_module_cjson(VM* vm){
+void add_module_cjson(VM* vm){
     PyObject* mod = vm->new_module("cjson");
     vm->bind_func<1>(mod, "loads", [](VM* vm, ArgsView args) {
 
diff --git a/CMakeLists.txt b/CMakeLists.txt
index dde0843e..7ad2ae5f 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -41,6 +41,7 @@ include_directories(${CMAKE_CURRENT_LIST_DIR}/include)
 aux_source_directory(${CMAKE_CURRENT_LIST_DIR}/src POCKETPY_SRC)
 
 option(PK_USE_BOX2D "Use Box2D" OFF)
+option(PK_USE_CJSON "Use cJSON" ON)
 option(PK_USE_DYLIB "Use dylib" OFF)
 
 if(PK_USE_BOX2D)
@@ -49,8 +50,11 @@ if(PK_USE_BOX2D)
     add_definitions(-DPK_USE_BOX2D)
 endif()
 
-add_subdirectory(${CMAKE_CURRENT_LIST_DIR}/3rd/cjson)
-include_directories(${CMAKE_CURRENT_LIST_DIR}/3rd/cjson/include)
+if(PK_USE_CJSON)
+    add_subdirectory(${CMAKE_CURRENT_LIST_DIR}/3rd/cjson)
+    include_directories(${CMAKE_CURRENT_LIST_DIR}/3rd/cjson/include)
+    add_definitions(-DPK_USE_CJSON)
+endif()
 
 # PK_IS_MAIN determines whether the project is being used from root
 # or if it is added as a dependency (through add_subdirectory for example).
diff --git a/src/pocketpy.cpp b/src/pocketpy.cpp
index 4be2a2e9..2b4d2bc2 100644
--- a/src/pocketpy.cpp
+++ b/src/pocketpy.cpp
@@ -4,11 +4,14 @@
 #include "box2dw.hpp"
 #endif
 
+#ifdef PK_USE_CJSON
+#include "cJSONw.hpp"
+#endif
+
 #if defined (_WIN32) && PK_SUPPORT_DYLIB == 1
 #define WIN32_LEAN_AND_MEAN
 #include <windows.h>
 #endif
-#include "cjson.hpp"
 
 namespace pkpy{
 
@@ -1713,7 +1716,6 @@ void VM::post_init(){
     add_module_traceback(this);
     add_module_time(this);
     add_module_json(this);
-    add_module_cjson(this);
     add_module_math(this);
     add_module_re(this);
     add_module_dis(this);
@@ -1750,6 +1752,10 @@ void VM::post_init(){
 #ifdef PK_USE_BOX2D
     add_module_box2d(this);
 #endif
+#ifdef PK_USE_CJSON
+    add_module_cjson(this);
+#endif
+
 #endif
 }