-SCM_INTERNAL void scm_unget_byte (int c, SCM port);
-SCM_INTERNAL void scm_unget_byte_unlocked (int c, SCM port);
+SCM_API void scm_unget_bytes (const unsigned char *buf, size_t len, SCM port);
+SCM_API void scm_unget_bytes_unlocked (const unsigned char *buf, size_t len, SCM port);
+SCM_API void scm_unget_byte (int c, SCM port);
+SCM_API void scm_unget_byte_unlocked (int c, SCM port);