diff -Naur json-c-0.9.old//json_util.c json-c-0.9//json_util.c
--- json-c-0.9.old//json_util.c	2009-12-15 23:53:18.000000000 +0000
+++ json-c-0.9//json_util.c	2009-12-16 00:37:37.000000000 +0000
@@ -52,7 +52,7 @@
 #include "json_tokener.h"
 #include "json_util.h"
 
-struct json_object* json_object_from_file(char *filename)
+struct json_object* json_object_from_file(const char *filename)
 {
   struct printbuf *pb;
   struct json_object *obj;
diff -Naur json-c-0.9.old//json_util.h json-c-0.9//json_util.h
--- json-c-0.9.old//json_util.h	2009-12-15 23:53:18.000000000 +0000
+++ json-c-0.9//json_util.h	2009-12-16 00:37:52.000000000 +0000
@@ -21,7 +21,7 @@
 #define JSON_FILE_BUF_SIZE 4096
 
 /* utility functions */
-extern struct json_object* json_object_from_file(char *filename);
+extern struct json_object* json_object_from_file(const char *filename);
 extern int json_object_to_file(char *filename, struct json_object *obj);
 
 #ifdef __cplusplus