C11 %zd is bit overkill here. Especially requiring conditional compile.

examples/simple_parse.c

@@ -90,11 +90,7 @@ void print_json_object(json_t *element, int indent) {
     print_json_indent(indent);
     size = json_object_size(element);
 
-#if defined(__STDC_VERSION__) && __STDC_VERSION__ >= 201112L
-    printf("JSON Object of %zd pair%s:\n", size, json_plural(size));
-#else
     printf("JSON Object of %lld pair%s:\n", (long long)size, json_plural(size));
-#endif
     json_object_foreach(element, key, value) {
         print_json_indent(indent + 2);
         printf("JSON Key: \"%s\"\n", key);
@@ -107,11 +103,7 @@ void print_json_array(json_t *element, int indent) {
     size_t size = json_array_size(element);
     print_json_indent(indent);
 
-#if defined(__STDC_VERSION__) && __STDC_VERSION__ >= 201112L
-    printf("JSON Array of %zd element%s:\n", size, json_plural(size));
-#else
     printf("JSON Array of %lld element%s:\n", (long long)size, json_plural(size));
-#endif
     for (i = 0; i < size; i++) {
         print_json_aux(json_array_get(element, i), indent + 2);
     }