diff --git a/c/bits.h b/c/bits.h
index 5f2ea68..e98f53c 100644
--- a/c/bits.h
+++ b/c/bits.h
@@ -1,6 +1,6 @@
 /* bits.h - bits functions.
  *
- * Copyright (C) 2021 Bruno Raoult ("br")
+ * Copyright (C) 2021-2022 Bruno Raoult ("br")
  * Licensed under the GNU General Public License v3.0 or later.
  * Some rights reserved. See COPYING.
  *
@@ -26,7 +26,7 @@
 /* no plan to support 32bits for now...
  */
 #if __WORDSIZE != 64
-ERROR_64_BYTES_WORDSIZE_ONLY
+#error "Only 64 bits word size supported."
 #endif
 
 typedef int64_t  s64;