diff --git a/sbin/tunefs/tunefs.c b/sbin/tunefs/tunefs.c
index 2ad01c0b3f1f..15c6cf075bca 100644
--- a/sbin/tunefs/tunefs.c
+++ b/sbin/tunefs/tunefs.c
@@ -84,8 +84,8 @@ static void sbdirty(void);
 int
 main(int argc, char *argv[])
 {
-	char *avalue, *jvalue, *Jvalue, *Lvalue, *lvalue, *Nvalue, *nvalue;
-	char *tvalue;
+	const char *avalue, *jvalue, *Jvalue, *Lvalue, *lvalue, *Nvalue, *nvalue;
+	const char *tvalue;
 	const char *special, *on;
 	const char *name;
 	int active;
@@ -711,7 +711,7 @@ journal_findfile(void)
 }
 
 static void
-dir_clear_block(char *block, off_t off)
+dir_clear_block(const char *block, off_t off)
 {
 	struct direct *dp;