diff --git a/src/xheader.c b/src/xheader.c
index 31676384..493a955c 100644
--- a/src/xheader.c
+++ b/src/xheader.c
@@ -615,7 +615,8 @@ extended_header_init (void)
 }
 
 void
-xheader_store (char const *keyword, struct tar_stat_info const *st, void *data)
+xheader_store (char const *keyword, struct tar_stat_info const *st,
+	       void const *data)
 {
   struct xhdr_tab const *t;