diff --git a/src/shared/socket-netlink.c b/src/shared/socket-netlink.c
index d72a70503a..e117459c10 100644
--- a/src/shared/socket-netlink.c
+++ b/src/shared/socket-netlink.c
@@ -464,7 +464,14 @@ struct in_addr_full *in_addr_full_free(struct in_addr_full *a) {
         return mfree(a);
 }
 
-int in_addr_full_new(int family, union in_addr_union *a, uint16_t port, int ifindex, const char *server_name, struct in_addr_full **ret) {
+int in_addr_full_new(
+                int family,
+                const union in_addr_union *a,
+                uint16_t port,
+                int ifindex,
+                const char *server_name,
+                struct in_addr_full **ret) {
+
         _cleanup_free_ char *name = NULL;
         struct in_addr_full *x;
 
diff --git a/src/shared/socket-netlink.h b/src/shared/socket-netlink.h
index 9517f6dd6d..e6cd7d9bf1 100644
--- a/src/shared/socket-netlink.h
+++ b/src/shared/socket-netlink.h
@@ -45,6 +45,6 @@ struct in_addr_full {
 
 struct in_addr_full *in_addr_full_free(struct in_addr_full *a);
 DEFINE_TRIVIAL_CLEANUP_FUNC(struct in_addr_full*, in_addr_full_free);
-int in_addr_full_new(int family, union in_addr_union *a, uint16_t port, int ifindex, const char *server_name, struct in_addr_full **ret);
+int in_addr_full_new(int family, const union in_addr_union *a, uint16_t port, int ifindex, const char *server_name, struct in_addr_full **ret);
 int in_addr_full_new_from_string(const char *s, struct in_addr_full **ret);
 const char *in_addr_full_to_string(struct in_addr_full *a);