diff --git a/src/logic/tpax_archive_write.c b/src/logic/tpax_archive_write.c
index f01bb7b..fbf46a7 100644
--- a/src/logic/tpax_archive_write.c
+++ b/src/logic/tpax_archive_write.c
@@ -15,11 +15,11 @@
 
 static int tpax_archive_append_memory_data(
 	int                             fdout,
-	void *                          buf,
+	const void *                    buf,
 	ssize_t                         nbytes)
 {
-	ssize_t ret;
-	char  * ch;
+	ssize_t       ret;
+	const char *  ch;
 
 	for (ch=buf; nbytes; ch+=ret) {
 		ret = write(fdout,ch,nbytes);