diff --git a/demos/tunala/cb.c b/demos/tunala/cb.c
index f35d8f75dcf5ef004446a5a51a7c5e0527a5bcfa..cd32f74c70a2c723af58faf69ee0f34e7e75fdb6 100644
--- a/demos/tunala/cb.c
+++ b/demos/tunala/cb.c
@@ -17,7 +17,7 @@ static int int_verify_depth = 10;
 
 /* This function is largely borrowed from the one used in OpenSSL's "s_client"
  * and "s_server" utilities. */
-void cb_ssl_info(SSL *s, int where, int ret)
+void cb_ssl_info(const SSL *s, int where, int ret)
 {
 	const char *str1, *str2;
 	int w;
diff --git a/demos/tunala/tunala.h b/demos/tunala/tunala.h
index 4271a4d4a817d625378e9ce10980bd3b87bb8083..b4c8ec78d8acfa727efbb1254b828704e26d38c9 100644
--- a/demos/tunala/tunala.h
+++ b/demos/tunala/tunala.h
@@ -143,7 +143,7 @@ void buffer_from_BIO(buffer_t *buf, BIO *bio);
 void buffer_to_BIO(buffer_t *buf, BIO *bio);
 
 /* Callbacks */
-void cb_ssl_info(SSL *s, int where, int ret);
+void cb_ssl_info(const SSL *s, int where, int ret);
 void cb_ssl_info_set_output(FILE *fp); /* Called if output should be sent too */
 int cb_ssl_verify(int ok, X509_STORE_CTX *ctx);
 void cb_ssl_verify_set_output(FILE *fp);