diff --git a/src/plugins/clangpchmanager/projectupdater.cpp b/src/plugins/clangpchmanager/projectupdater.cpp
index ff07f40a02d..a36689b3b74 100644
--- a/src/plugins/clangpchmanager/projectupdater.cpp
+++ b/src/plugins/clangpchmanager/projectupdater.cpp
@@ -188,7 +188,7 @@ ClangBackEnd::V2::ProjectPartContainer ProjectUpdater::toProjectPartContainer(
 
     HeaderAndSources headerAndSources = headerAndSourcesFromProjectPart(projectPart);
 
-    return ClangBackEnd::V2::ProjectPartContainer(projectPart->displayName,
+    return ClangBackEnd::V2::ProjectPartContainer(projectPart->id(),
                                                   Utils::SmallStringVector(arguments),
                                                   createCompilerMacros(projectPart->projectMacros),
                                                   createIncludeSearchPaths(projectPart->headerPaths),
diff --git a/tests/unit/unittest/projectupdater-test.cpp b/tests/unit/unittest/projectupdater-test.cpp
index 5fa1b0e5686..7b0b38004a7 100644
--- a/tests/unit/unittest/projectupdater-test.cpp
+++ b/tests/unit/unittest/projectupdater-test.cpp
@@ -82,15 +82,18 @@ protected:
         projectPart.files.push_back(header2ProjectFile);
         projectPart.files.push_back(source1ProjectFile);
         projectPart.files.push_back(source2ProjectFile);
-        projectPart.displayName = QString(projectPartId);
+        projectPart.displayName = "project1";
         projectPart.projectMacros = {{"FOO", "2"}, {"BAR", "1"}};
+        projectPartId = projectPart.id();
 
         projectPart2.files.push_back(header2ProjectFile);
         projectPart2.files.push_back(header1ProjectFile);
         projectPart2.files.push_back(source2ProjectFile);
         projectPart2.files.push_back(source1ProjectFile);
-        projectPart2.displayName = QString(projectPartId2);
+        projectPart2.displayName = "project2";
         projectPart2.projectMacros = {{"BAR", "1"}, {"FOO", "2"}};
+        projectPartId2 = projectPart2.id();
+
 
         Utils::SmallStringVector arguments{ClangPchManager::ProjectUpdater::compilerArguments(
                         &projectPart)};
@@ -120,8 +123,8 @@ protected:
     MockPchManagerNotifier mockPchManagerNotifier{pchManagerClient};
     NiceMock<MockPchManagerServer> mockPchManagerServer;
     ClangPchManager::ProjectUpdater updater{mockPchManagerServer, filePathCache};
-    Utils::SmallString projectPartId{"project1"};
-    Utils::SmallString projectPartId2{"project2"};
+    Utils::SmallString projectPartId;
+    Utils::SmallString projectPartId2;
     Utils::PathStringVector headerPaths = {"/path/to/header1.h", "/path/to/header2.h"};
     Utils::PathStringVector sourcePaths = {"/path/to/source1.cpp", "/path/to/source2.cpp"};
     ClangBackEnd::CompilerMacros compilerMacros = {{"BAR", "1"}, {"FOO", "2"}};