diff --git a/src/libsystemd-network/sd-dhcp6-client.c b/src/libsystemd-network/sd-dhcp6-client.c
index 6c017e0ff9..99f38382e9 100644
--- a/src/libsystemd-network/sd-dhcp6-client.c
+++ b/src/libsystemd-network/sd-dhcp6-client.c
@@ -382,7 +382,7 @@ int sd_dhcp6_client_set_request_option(sd_dhcp6_client *client, uint16_t option)
         return 0;
 }
 
-int sd_dhcp6_client_set_request_mud_url(sd_dhcp6_client *client, char *mudurl) {
+int sd_dhcp6_client_set_request_mud_url(sd_dhcp6_client *client, const char *mudurl) {
 
         assert_return(client, -EINVAL);
         assert_return(client->state == DHCP6_STATE_STOPPED, -EBUSY);
diff --git a/src/systemd/sd-dhcp6-client.h b/src/systemd/sd-dhcp6-client.h
index 42d4ec752c..091f8287ec 100644
--- a/src/systemd/sd-dhcp6-client.h
+++ b/src/systemd/sd-dhcp6-client.h
@@ -123,7 +123,7 @@ int sd_dhcp6_client_set_request_option(
                 uint16_t option);
 int sd_dhcp6_client_set_request_mud_url(
                 sd_dhcp6_client *client,
-                char *mudurl);
+                const char *mudurl);
 int sd_dhcp6_client_set_prefix_delegation_hint(
                 sd_dhcp6_client *client,
                 uint8_t prefixlen,