--- a/libtextstyle/lib/iconv-ostream.c
+++ b/libtextstyle/lib/iconv-ostream.c
@@ -231,7 +231,7 @@ iconv_ostream__write_mem (iconv_ostream_t stream, const void *data, size_t len)
 }
 
 static void
-iconv_ostream__flush (iconv_ostream_t stream)
+iconv_ostream__flush (iconv_ostream_t stream, ostream_flush_scope_t scope)
 {
   abort ();
 }