diff --git a/src/libsystemd-network/ndisc-router.c b/src/libsystemd-network/ndisc-router.c
index 74331591f0..5162df799c 100644
--- a/src/libsystemd-network/ndisc-router.c
+++ b/src/libsystemd-network/ndisc-router.c
@@ -593,7 +593,7 @@ int sd_ndisc_router_route_get_preference(sd_ndisc_router *rt, unsigned *ret) {
                 return r;
 
         if (!IN_SET((ri[3] >> 3) & 3, SD_NDISC_PREFERENCE_LOW, SD_NDISC_PREFERENCE_MEDIUM, SD_NDISC_PREFERENCE_HIGH))
-                return -ENOTSUP;
+                return -EOPNOTSUPP;
 
         *ret = (ri[3] >> 3) & 3;
         return 0;