diff --git a/Common/s2j/s2j.h b/Common/s2j/s2j.h
index b09a9f759..f6ba49b77 100644
--- a/Common/s2j/s2j.h
+++ b/Common/s2j/s2j.h
@@ -81,8 +81,26 @@ extern "C" {
     S2J_STRUCT_GET_STRUCT_ELEMENT(child_struct, to_struct, child_json, from_json, type, element)
 
 /* s2j.c */
-extern S2jHook s2jHook;
-void s2j_init(S2jHook *hook);
+//extern S2jHook s2jHook;
+
+S2jHook s2jHook = {
+        .malloc_fn = malloc,
+        .free_fn = free,
+};
+
+static void s2j_init(S2jHook *hook)
+{
+    /* initialize cJSON library */
+    cJSON_InitHooks((cJSON_Hooks *)hook);
+    /* initialize hooks */
+    if (hook) {
+        s2jHook.malloc_fn = (hook->malloc_fn) ? hook->malloc_fn : malloc;
+        s2jHook.free_fn = (hook->free_fn) ? hook->free_fn : free;
+    } else {
+        s2jHook.malloc_fn = malloc;
+        s2jHook.free_fn = free;
+    }
+}
 
 #ifdef __cplusplus
 }