diff --git a/src/ethernet_interface.cpp b/src/ethernet_interface.cpp
index 3374c6f..a577c2a 100644
--- a/src/ethernet_interface.cpp
+++ b/src/ethernet_interface.cpp
@@ -237,6 +237,10 @@
             default:
                 throw std::logic_error("Exhausted protocols");
         }
+        if (!std::visit([](auto ip) { return validIntfIP(ip); }, *addr))
+        {
+            throw std::invalid_argument("not unicast");
+        }
     }
     catch (const std::exception& e)
     {
@@ -248,6 +252,10 @@
     std::optional<stdplus::SubnetAny> ifaddr;
     try
     {
+        if (prefixLength == 0)
+        {
+            throw std::invalid_argument("default route");
+        }
         ifaddr.emplace(*addr, prefixLength);
     }
     catch (const std::exception& e)
diff --git a/test/test_ethernet_interface.cpp b/test/test_ethernet_interface.cpp
index 21062f4..74768c1 100644
--- a/test/test_ethernet_interface.cpp
+++ b/test/test_ethernet_interface.cpp
@@ -96,6 +96,19 @@
 
 TEST_F(TestEthernetInterface, AddIPAddress)
 {
+    EXPECT_THROW(createIPObject(IP::Protocol::IPv4, "127.0.0.1", 16),
+                 InvalidArgument);
+    EXPECT_THROW(createIPObject(IP::Protocol::IPv4, "127.0.0.1", 32),
+                 InvalidArgument);
+    EXPECT_THROW(createIPObject(IP::Protocol::IPv4, "192.168.1.1", 0),
+                 InvalidArgument);
+    EXPECT_THROW(createIPObject(IP::Protocol::IPv6, "::1", 64),
+                 InvalidArgument);
+    EXPECT_THROW(createIPObject(IP::Protocol::IPv6, "::", 128),
+                 InvalidArgument);
+    EXPECT_THROW(createIPObject(IP::Protocol::IPv6, "fe80::1", 0),
+                 InvalidArgument);
+
     createIPObject(IP::Protocol::IPv4, "10.10.10.10", 16);
     EXPECT_THAT(interface.addrs, UnorderedElementsAre(Key(stdplus::SubnetAny(
                                      stdplus::In4Addr{10, 10, 10, 10}, 16))));