doh: Constify some input pointers

Closes #5306

1 files changed, 1 insertions, 1 deletions

diff --git a/lib/doh.h b/lib/doh.h
index fc053eddf..97d459f09 100644
--- a/lib/doh.h
+++ b/lib/doh.h
@@ -99,7 +99,7 @@ DOHcode doh_encode(const char *host,
                    unsigned char *dnsp, /* buffer */
                    size_t len,  /* buffer size */
                    size_t *olen); /* output length */
-DOHcode doh_decode(unsigned char *doh,
+DOHcode doh_decode(const unsigned char *doh,
                    size_t dohlen,
                    DNStype dnstype,
                    struct dohentry *d);