diff --git a/test/openpower-pels/mocks.hpp b/test/openpower-pels/mocks.hpp
index 1fd679f..be3291d 100644
--- a/test/openpower-pels/mocks.hpp
+++ b/test/openpower-pels/mocks.hpp
@@ -32,9 +32,10 @@
     MOCK_METHOD(void, getHWCalloutFields,
                 (const std::string&, std::string&, std::string&, std::string&),
                 (const override));
-    MOCK_METHOD(std::string, getSystemType, (), (const override));
     MOCK_METHOD(std::string, getLocationCode, (const std::string&),
                 (const override));
+    MOCK_METHOD(const std::vector<std::string>&, getSystemNames, (),
+                (const override));
 
     void changeHostState(bool newState)
     {
diff --git a/test/openpower-pels/registry_test.cpp b/test/openpower-pels/registry_test.cpp
index ec930e9..fa1aa0c 100644
--- a/test/openpower-pels/registry_test.cpp
+++ b/test/openpower-pels/registry_test.cpp
@@ -362,6 +362,8 @@
 // Test when callouts are in the JSON.
 TEST_F(RegistryTest, TestGetCallouts)
 {
+    std::vector<std::string> names;
+
     {
         // Callouts without AD, that depend on system type,
         // where there is a default entry without a system type.
@@ -403,8 +405,9 @@
         ])"_json;
 
         AdditionalData ad;
+        names.push_back("system1");
 
-        auto callouts = Registry::getCallouts(json, "system1", ad);
+        auto callouts = Registry::getCallouts(json, names, ad);
         EXPECT_EQ(callouts.size(), 3);
         EXPECT_EQ(callouts[0].priority, "high");
         EXPECT_EQ(callouts[0].locCode, "P1-C1");
@@ -423,7 +426,8 @@
         EXPECT_EQ(callouts[2].symbolicFRUTrusted, "");
 
         // system2 isn't in the JSON, so it will pick the default one
-        callouts = Registry::getCallouts(json, "system2", ad);
+        names[0] = "system2";
+        callouts = Registry::getCallouts(json, names, ad);
         EXPECT_EQ(callouts.size(), 2);
         EXPECT_EQ(callouts[0].priority, "medium");
         EXPECT_EQ(callouts[0].locCode, "");
@@ -440,7 +444,8 @@
     {
         auto json = R"([])"_json;
         AdditionalData ad;
-        EXPECT_THROW(Registry::getCallouts(json, "system1", ad),
+        names[0] = "system1";
+        EXPECT_THROW(Registry::getCallouts(json, names, ad),
                      std::runtime_error);
     }
 
@@ -479,8 +484,9 @@
         ])"_json;
 
         AdditionalData ad;
+        names[0] = "system1";
 
-        auto callouts = Registry::getCallouts(json, "system1", ad);
+        auto callouts = Registry::getCallouts(json, names, ad);
         EXPECT_EQ(callouts.size(), 2);
         EXPECT_EQ(callouts[0].priority, "high");
         EXPECT_EQ(callouts[0].locCode, "P1-C1");
@@ -493,7 +499,8 @@
         EXPECT_EQ(callouts[1].symbolicFRU, "1234567");
         EXPECT_EQ(callouts[1].symbolicFRUTrusted, "");
 
-        callouts = Registry::getCallouts(json, "system2", ad);
+        names[0] = "system2";
+        callouts = Registry::getCallouts(json, names, ad);
         EXPECT_EQ(callouts.size(), 1);
         EXPECT_EQ(callouts[0].priority, "medium");
         EXPECT_EQ(callouts[0].locCode, "P7");
@@ -503,7 +510,8 @@
 
         // There is no entry for system3 or a default system,
         // so this should fail.
-        EXPECT_THROW(Registry::getCallouts(json, "system3", ad),
+        names[0] = "system3";
+        EXPECT_THROW(Registry::getCallouts(json, names, ad),
                      std::runtime_error);
     }
 
@@ -574,8 +582,9 @@
             // Find callouts for PROC_NUM 0 on system3
             std::vector<std::string> adData{"PROC_NUM=0"};
             AdditionalData ad{adData};
+            names[0] = "system3";
 
-            auto callouts = Registry::getCallouts(json, "system3", ad);
+            auto callouts = Registry::getCallouts(json, names, ad);
             EXPECT_EQ(callouts.size(), 3);
             EXPECT_EQ(callouts[0].priority, "high");
             EXPECT_EQ(callouts[0].locCode, "P1-C5");
@@ -594,7 +603,9 @@
             EXPECT_EQ(callouts[2].symbolicFRUTrusted, "");
 
             // Find callouts for PROC_NUM 0 that uses the default system entry.
-            callouts = Registry::getCallouts(json, "system99", ad);
+            names[0] = "system99";
+
+            callouts = Registry::getCallouts(json, names, ad);
             EXPECT_EQ(callouts.size(), 1);
             EXPECT_EQ(callouts[0].priority, "low");
             EXPECT_EQ(callouts[0].locCode, "P55");
@@ -606,8 +617,9 @@
             // Find callouts for PROC_NUM 1 that uses a default system entry.
             std::vector<std::string> adData{"PROC_NUM=1"};
             AdditionalData ad{adData};
+            names[0] = "system1";
 
-            auto callouts = Registry::getCallouts(json, "system1", ad);
+            auto callouts = Registry::getCallouts(json, names, ad);
             EXPECT_EQ(callouts.size(), 1);
             EXPECT_EQ(callouts[0].priority, "high");
             EXPECT_EQ(callouts[0].locCode, "P1-C6");
@@ -620,7 +632,7 @@
             std::vector<std::string> adData{"PROC_NUM=2"};
             AdditionalData ad{adData};
 
-            EXPECT_THROW(Registry::getCallouts(json, "system1", ad),
+            EXPECT_THROW(Registry::getCallouts(json, names, ad),
                          std::runtime_error);
         }
     }
diff --git a/test/openpower-pels/src_test.cpp b/test/openpower-pels/src_test.cpp
index e9abb8e..d767c53 100644
--- a/test/openpower-pels/src_test.cpp
+++ b/test/openpower-pels/src_test.cpp
@@ -26,6 +26,7 @@
 using ::testing::InvokeWithoutArgs;
 using ::testing::NiceMock;
 using ::testing::Return;
+using ::testing::ReturnRef;
 using ::testing::SetArgReferee;
 namespace fs = std::filesystem;
 
@@ -517,7 +518,9 @@
         // Call out a symbolic FRU and a procedure
         AdditionalData ad;
         NiceMock<MockDataInterface> dataIface;
-        EXPECT_CALL(dataIface, getSystemType).WillOnce(Return("systemA"));
+        std::vector<std::string> names{"systemA"};
+
+        EXPECT_CALL(dataIface, getSystemNames).WillOnce(ReturnRef(names));
 
         SRC src{entry, ad, dataIface};
 
@@ -551,7 +554,9 @@
         // another one without.
         AdditionalData ad;
         NiceMock<MockDataInterface> dataIface;
-        EXPECT_CALL(dataIface, getSystemType).WillOnce(Return("systemB"));
+        std::vector<std::string> names{"systemB"};
+
+        EXPECT_CALL(dataIface, getSystemNames).WillOnce(ReturnRef(names));
 
         SRC src{entry, ad, dataIface};
 
diff --git a/test/openpower-pels/user_header_test.cpp b/test/openpower-pels/user_header_test.cpp
index f37b085..546b480 100644
--- a/test/openpower-pels/user_header_test.cpp
+++ b/test/openpower-pels/user_header_test.cpp
@@ -24,6 +24,7 @@
 
 using namespace openpower::pels;
 using ::testing::Return;
+using ::testing::ReturnRef;
 
 TEST(UserHeaderTest, SizeTest)
 {
@@ -112,7 +113,9 @@
         regEntry.eventScope = 2;
 
         MockDataInterface dataIface;
-        EXPECT_CALL(dataIface, getSystemType).WillOnce(Return("systemA"));
+        std::vector<std::string> names{"systemA"};
+
+        EXPECT_CALL(dataIface, getSystemNames).WillOnce(ReturnRef(names));
 
         UserHeader uh(regEntry, phosphor::logging::Entry::Level::Error,
                       dataIface);
@@ -143,10 +146,14 @@
         regEntry.severity = {{"", 0x20}, {"systemB", 0x10}, {"systemA", 0x00}};
 
         MockDataInterface dataIface;
-        EXPECT_CALL(dataIface, getSystemType)
-            .WillOnce(Return("systemA"))
-            .WillOnce(Return("systemB"))
-            .WillOnce(Return("systemC"));
+        std::vector<std::string> names1{"systemA"};
+        std::vector<std::string> names2{"systemB"};
+        std::vector<std::string> names3{"systemC"};
+
+        EXPECT_CALL(dataIface, getSystemNames)
+            .WillOnce(ReturnRef(names1))
+            .WillOnce(ReturnRef(names2))
+            .WillOnce(ReturnRef(names3));
 
         {
             UserHeader uh(regEntry, phosphor::logging::Entry::Level::Error,
@@ -204,6 +211,9 @@
 
     MockDataInterface dataIface;
 
+    std::vector<std::string> names{"systemA"};
+    EXPECT_CALL(dataIface, getSystemNames).WillOnce(ReturnRef(names));
+
     UserHeader uh(regEntry, phosphor::logging::Entry::Level::Error, dataIface);
 
     ASSERT_EQ(uh.eventType(), 0);