diff --git a/src/network/networkd-radv.c b/src/network/networkd-radv.c
index 5475ed787e..1cd605a722 100644
--- a/src/network/networkd-radv.c
+++ b/src/network/networkd-radv.c
@@ -731,6 +731,8 @@ int config_parse_prefix(
                            "Prefix is invalid, ignoring assignment: %s", rvalue);
                 return 0;
         }
+
+        (void) in6_addr_mask(&a.in6, p->prefixlen);
         p->prefix = a.in6;
 
         TAKE_PTR(p);
@@ -940,6 +942,8 @@ int config_parse_route_prefix(
                            "Route prefix is invalid, ignoring assignment: %s", rvalue);
                 return 0;
         }
+
+        (void) in6_addr_mask(&a.in6, p->prefixlen);
         p->prefix = a.in6;
 
         TAKE_PTR(p);