diff --git a/ssh.h b/ssh.h
index 47feb92f..b76ecefc 100644
--- a/ssh.h
+++ b/ssh.h
@@ -726,7 +726,7 @@ struct ssh2_macalg {
 
 #define ssh2_mac_new(alg, cipher) ((alg)->new(alg, cipher))
 #define ssh2_mac_free(ctx) ((ctx)->vt->free(ctx))
-#define ssh2_mac_setkey(ctx, key) ((ctx)->vt->free(ctx, key))
+#define ssh2_mac_setkey(ctx, key) ((ctx)->vt->setkey(ctx, key))
 #define ssh2_mac_start(ctx) ((ctx)->vt->start(ctx))
 #define ssh2_mac_genresult(ctx, out) ((ctx)->vt->genresult(ctx, out))
 #define ssh2_mac_alg(ctx) ((ctx)->vt)
diff --git a/ssh2bpp.c b/ssh2bpp.c
index 67d8306f..2e73b56e 100644
--- a/ssh2bpp.c
+++ b/ssh2bpp.c
@@ -122,7 +122,7 @@ void ssh2_bpp_new_outgoing_crypto(
     s->out.etm_mode = etm_mode;
     if (mac) {
         s->out.mac = ssh2_mac_new(mac, s->out.cipher);
-        mac->setkey(s->out.mac, mac_key);
+        ssh2_mac_setkey(s->out.mac, mac_key);
 
         bpp_logevent("Initialised %s outbound MAC algorithm%s%s",
                      ssh2_mac_alg(s->out.mac)->text_name,
@@ -184,7 +184,7 @@ void ssh2_bpp_new_incoming_crypto(
     s->in.etm_mode = etm_mode;
     if (mac) {
         s->in.mac = ssh2_mac_new(mac, s->in.cipher);
-        mac->setkey(s->in.mac, mac_key);
+        ssh2_mac_setkey(s->in.mac, mac_key);
 
         bpp_logevent("Initialised %s inbound MAC algorithm%s%s",
                      ssh2_mac_alg(s->in.mac)->text_name,