diff --git a/c/scheme48.h b/c/scheme48.h
index b22d05e..9ec9498 100644
--- a/c/scheme48.h
+++ b/c/scheme48.h
@@ -457,7 +457,7 @@ extern void s48_check_record_type(s48_value record, s48_value type_binding);
 #define S48_RECORD_SET(x, i, v) (s48_stob_set((x), S48_STOBTYPE_RECORD, (i) + 1, (v)))
 #define S48_UNSAFE_RECORD_REF(x, i) (S48_STOB_REF((x), (i) + 1))
 #define S48_UNSAFE_RECORD_SET(x, i, v) S48_STOB_SET((x), (i) + 1, (v))
-#define S48_RECORD_TYPE(x) (s48_stob_ref((x), S48_STOBTYPE_RECORD))
+#define S48_RECORD_TYPE(x) (s48_stob_ref((x), S48_STOBTYPE_RECORD, 0))
 #define S48_UNSAFE_RECORD_TYPE(x) (STOB_REF((x), 0))
 #define S48_BYTE_VECTOR_LENGTH(x) (s48_stob_byte_length((x), S48_STOBTYPE_BYTE_VECTOR))
 #define S48_BYTE_VECTOR_REF(x, i) (s48_stob_byte_ref((x), S48_STOBTYPE_BYTE_VECTOR, (i)))