diff --git a/src/openvpn/options.c b/src/openvpn/options.c
index e42029c..1927a32 100644
--- a/src/openvpn/options.c
+++ b/src/openvpn/options.c
@@ -3509,7 +3509,7 @@ calc_options_string_link_mtu(const struct options *o, const struct frame *frame)
         struct key_type fake_kt;
         init_key_type(&fake_kt, o->ciphername, o->authname, o->keysize, true,
                       false);
-        frame_add_to_extra_frame(&fake_frame, -(crypto_max_overhead()));
+        frame_add_to_extra_frame(&fake_frame, -(int)(crypto_max_overhead()));
         crypto_adjust_frame_parameters(&fake_frame, &fake_kt, o->replay,
                                        cipher_kt_mode_ofb_cfb(fake_kt.cipher));
         frame_finalize(&fake_frame, o->ce.link_mtu_defined, o->ce.link_mtu,
diff --git a/src/openvpn/ssl.c b/src/openvpn/ssl.c
index 315303b..18b1fbd 100644
--- a/src/openvpn/ssl.c
+++ b/src/openvpn/ssl.c
@@ -1987,7 +1987,7 @@ tls_session_update_crypto_params(struct tls_session *session,
     }
 
     /* Update frame parameters: undo worst-case overhead, add actual overhead */
-    frame_add_to_extra_frame(frame, -(crypto_max_overhead()));
+    frame_add_to_extra_frame(frame, -(int)(crypto_max_overhead()));
     crypto_adjust_frame_parameters(frame, &session->opt->key_type,
                                    options->replay, packet_id_long_form);
     frame_finalize(frame, options->ce.link_mtu_defined, options->ce.link_mtu,