diff --git a/test/test_util.cpp b/test/test_util.cpp
index 437b3cf..6c647ed 100644
--- a/test/test_util.cpp
+++ b/test/test_util.cpp
@@ -2,6 +2,8 @@
 
 #include <netinet/in.h>
 
+#include <xyz/openbmc_project/Common/error.hpp>
+
 #include <gtest/gtest.h>
 
 namespace phosphor
@@ -9,6 +11,8 @@
 namespace network
 {
 
+using InternalFailure =
+    sdbusplus::xyz::openbmc_project::Common::Error::InternalFailure;
 class TestUtil : public testing::Test
 {
   public:
@@ -184,11 +188,10 @@
     address = getNetworkID(AF_INET6, "2001:db8:abcd:dd12::0", 64);
     EXPECT_EQ("2001:db8:abcd:dd12::", address);
 
-    address = getNetworkID(AF_INET, "a.b.c.d", 25);
-    EXPECT_EQ("", address);
+    EXPECT_THROW(getNetworkID(AF_INET, "a.b.c.d", 25), InternalFailure);
 
-    address = getNetworkID(AF_INET6, "2001:db8:gghh:dd12::0", 64);
-    EXPECT_EQ("", address);
+    EXPECT_THROW(getNetworkID(AF_INET6, "2001:db8:gghh:dd12::0", 64),
+                 InternalFailure);
 
     address = getNetworkID(AF_INET6, "fe80::201:6cff:fe80:228", 64);
     EXPECT_EQ("fe80::", address);