diff --git a/src/libsystemd-network/lldp-neighbor.c b/src/libsystemd-network/lldp-neighbor.c
index b056019989..f8394c4374 100644
--- a/src/libsystemd-network/lldp-neighbor.c
+++ b/src/libsystemd-network/lldp-neighbor.c
@@ -116,6 +116,9 @@ sd_lldp_neighbor *lldp_neighbor_unlink(sd_lldp_neighbor *n) {
 sd_lldp_neighbor *lldp_neighbor_new(size_t raw_size) {
         sd_lldp_neighbor *n;
 
+        if (raw_size > SIZE_MAX - ALIGN(sizeof(sd_lldp_neighbor)))
+                return NULL;
+
         n = malloc0(ALIGN(sizeof(sd_lldp_neighbor)) + raw_size);
         if (!n)
                 return NULL;
diff --git a/src/libsystemd-network/ndisc-router.c b/src/libsystemd-network/ndisc-router.c
index 464b002c2f..26615ac666 100644
--- a/src/libsystemd-network/ndisc-router.c
+++ b/src/libsystemd-network/ndisc-router.c
@@ -21,6 +21,9 @@ DEFINE_PUBLIC_TRIVIAL_REF_UNREF_FUNC(sd_ndisc_router, sd_ndisc_router, mfree);
 sd_ndisc_router *ndisc_router_new(size_t raw_size) {
         sd_ndisc_router *rt;
 
+        if (raw_size > SIZE_MAX - ALIGN(sizeof(sd_ndisc_router)))
+                return NULL;
+
         rt = malloc0(ALIGN(sizeof(sd_ndisc_router)) + raw_size);
         if (!rt)
                 return NULL;