diff --git a/Source/cmVSSolution.cxx b/Source/cmVSSolution.cxx
index f85231d9a6..eb750db077 100644
--- a/Source/cmVSSolution.cxx
+++ b/Source/cmVSSolution.cxx
@@ -312,6 +312,9 @@ void WriteSlnxProject(cmXMLElement& xmlParent, Solution const& solution,
   cmXMLElement xmlProject(xmlParent, "Project");
   xmlProject.Attribute("Path", project.Path);
   xmlProject.Attribute("Id", cmSystemTools::LowerCase(project.Id));
+  if (project.Name == solution.StartupProject) {
+    xmlProject.Attribute("DefaultStartup", "true");
+  }
   for (Solution::Project const* d : project.BuildDependencies) {
     cmXMLElement(xmlProject, "BuildDependency").Attribute("Project", d->Path);
   }
diff --git a/Tests/RunCMake/VSSolution/AddPackageToDefault-check-slnx.cmake b/Tests/RunCMake/VSSolution/AddPackageToDefault-check-slnx.cmake
index b60f278f40..320cab5ba3 100644
--- a/Tests/RunCMake/VSSolution/AddPackageToDefault-check-slnx.cmake
+++ b/Tests/RunCMake/VSSolution/AddPackageToDefault-check-slnx.cmake
@@ -8,7 +8,7 @@ RunCMake_check_slnx("${RunCMake_TEST_BINARY_DIR}/AddPackageToDefault.slnx" [[
     <BuildType Name="RelWithDebInfo"/>
     <Platform Name="[^"]+"/>
   </Configurations>
-  <Project Path="ALL_BUILD\.vcxproj" Id="[0-9a-f-]+">
+  <Project Path="ALL_BUILD\.vcxproj" Id="[0-9a-f-]+" DefaultStartup="true">
     <BuildDependency Project="ZERO_CHECK\.vcxproj"/>
   </Project>
   <Project Path="PACKAGE.vcxproj" Id="[0-9a-f-]+">
diff --git a/Tests/RunCMake/VSSolution/CMP0143-NEW-check-slnx.cmake b/Tests/RunCMake/VSSolution/CMP0143-NEW-check-slnx.cmake
index 67d10cb384..009e372791 100644
--- a/Tests/RunCMake/VSSolution/CMP0143-NEW-check-slnx.cmake
+++ b/Tests/RunCMake/VSSolution/CMP0143-NEW-check-slnx.cmake
@@ -16,7 +16,7 @@ RunCMake_check_slnx("${RunCMake_TEST_BINARY_DIR}/CMP0143-NEW.slnx" [[
     <Build Solution="RelWithDebInfo\|\*" Project="false"/>
   </Project>
   <Folder Name="/CMakePredefinedTargets/">
-    <Project Path="ALL_BUILD.vcxproj" Id="[0-9a-f-]+">
+    <Project Path="ALL_BUILD.vcxproj" Id="[0-9a-f-]+" DefaultStartup="true">
       <BuildDependency Project="ZERO_CHECK.vcxproj"/>
       <Build Solution="Debug\|\*" Project="false"/>
       <Build Solution="Release\|\*" Project="false"/>
diff --git a/Tests/RunCMake/VSSolution/CMP0143-OLD-check-slnx.cmake b/Tests/RunCMake/VSSolution/CMP0143-OLD-check-slnx.cmake
index cfcb5d43b6..7de36eefdf 100644
--- a/Tests/RunCMake/VSSolution/CMP0143-OLD-check-slnx.cmake
+++ b/Tests/RunCMake/VSSolution/CMP0143-OLD-check-slnx.cmake
@@ -8,7 +8,7 @@ RunCMake_check_slnx("${RunCMake_TEST_BINARY_DIR}/CMP0143-OLD.slnx" [[
     <BuildType Name="RelWithDebInfo"/>
     <Platform Name="[^"]+"/>
   </Configurations>
-  <Project Path="ALL_BUILD\.vcxproj" Id="[0-9a-f-]+">
+  <Project Path="ALL_BUILD\.vcxproj" Id="[0-9a-f-]+" DefaultStartup="true">
     <BuildDependency Project="ZERO_CHECK\.vcxproj"/>
     <Build Solution="Debug\|\*" Project="false"/>
     <Build Solution="Release\|\*" Project="false"/>
diff --git a/Tests/RunCMake/VSSolution/CMP0143-WARN-check-slnx.cmake b/Tests/RunCMake/VSSolution/CMP0143-WARN-check-slnx.cmake
index 0c51664732..863da1d379 100644
--- a/Tests/RunCMake/VSSolution/CMP0143-WARN-check-slnx.cmake
+++ b/Tests/RunCMake/VSSolution/CMP0143-WARN-check-slnx.cmake
@@ -8,7 +8,7 @@ RunCMake_check_slnx("${RunCMake_TEST_BINARY_DIR}/CMP0143-WARN.slnx" [[
     <BuildType Name="RelWithDebInfo"/>
     <Platform Name="[^"]+"/>
   </Configurations>
-  <Project Path="ALL_BUILD\.vcxproj" Id="[0-9a-f-]+">
+  <Project Path="ALL_BUILD\.vcxproj" Id="[0-9a-f-]+" DefaultStartup="true">
     <BuildDependency Project="ZERO_CHECK\.vcxproj"/>
     <Build Solution="Debug\|\*" Project="false"/>
     <Build Solution="Release\|\*" Project="false"/>
diff --git a/Tests/RunCMake/VSSolution/DeployEnabled-check-slnx.cmake b/Tests/RunCMake/VSSolution/DeployEnabled-check-slnx.cmake
index 94b297dc80..82b9c762c8 100644
--- a/Tests/RunCMake/VSSolution/DeployEnabled-check-slnx.cmake
+++ b/Tests/RunCMake/VSSolution/DeployEnabled-check-slnx.cmake
@@ -8,7 +8,7 @@ RunCMake_check_slnx("${RunCMake_TEST_BINARY_DIR}/DeployEnabled.slnx" [[
     <BuildType Name="RelWithDebInfo"/>
     <Platform Name="[^"]+"/>
   </Configurations>
-  <Project Path="ALL_BUILD\.vcxproj" Id="[0-9a-f-]+">
+  <Project Path="ALL_BUILD\.vcxproj" Id="[0-9a-f-]+" DefaultStartup="true">
     <BuildDependency Project="ZERO_CHECK\.vcxproj"/>
     <BuildDependency Project="foo\.vcxproj"/>
     <Build Solution="Debug\|\*" Project="false"/>
diff --git a/Tests/RunCMake/VSSolution/MorePost-check-slnx.cmake b/Tests/RunCMake/VSSolution/MorePost-check-slnx.cmake
index ef8173b42f..8cb982f191 100644
--- a/Tests/RunCMake/VSSolution/MorePost-check-slnx.cmake
+++ b/Tests/RunCMake/VSSolution/MorePost-check-slnx.cmake
@@ -8,7 +8,7 @@ RunCMake_check_slnx("${RunCMake_TEST_BINARY_DIR}/MorePost.slnx" [[
     <BuildType Name="RelWithDebInfo"/>
     <Platform Name="[^"]+"/>
   </Configurations>
-  <Project Path="ALL_BUILD\.vcxproj" Id="[0-9a-f-]+">
+  <Project Path="ALL_BUILD\.vcxproj" Id="[0-9a-f-]+" DefaultStartup="true">
     <BuildDependency Project="ZERO_CHECK\.vcxproj"/>
     <Build Solution="Debug\|\*" Project="false"/>
     <Build Solution="Release\|\*" Project="false"/>
diff --git a/Tests/RunCMake/VSSolution/MorePre-check-slnx.cmake b/Tests/RunCMake/VSSolution/MorePre-check-slnx.cmake
index d025b6c6bf..65c82a53bf 100644
--- a/Tests/RunCMake/VSSolution/MorePre-check-slnx.cmake
+++ b/Tests/RunCMake/VSSolution/MorePre-check-slnx.cmake
@@ -8,7 +8,7 @@ RunCMake_check_slnx("${RunCMake_TEST_BINARY_DIR}/MorePre.slnx" [[
     <BuildType Name="RelWithDebInfo"/>
     <Platform Name="[^"]+"/>
   </Configurations>
-  <Project Path="ALL_BUILD\.vcxproj" Id="[0-9a-f-]+">
+  <Project Path="ALL_BUILD\.vcxproj" Id="[0-9a-f-]+" DefaultStartup="true">
     <BuildDependency Project="ZERO_CHECK\.vcxproj"/>
     <Build Solution="Debug\|\*" Project="false"/>
     <Build Solution="Release\|\*" Project="false"/>
diff --git a/Tests/RunCMake/VSSolution/OnePost-check-slnx.cmake b/Tests/RunCMake/VSSolution/OnePost-check-slnx.cmake
index 4556be6bfd..a76d41c0bd 100644
--- a/Tests/RunCMake/VSSolution/OnePost-check-slnx.cmake
+++ b/Tests/RunCMake/VSSolution/OnePost-check-slnx.cmake
@@ -8,7 +8,7 @@ RunCMake_check_slnx("${RunCMake_TEST_BINARY_DIR}/OnePost.slnx" [[
     <BuildType Name="RelWithDebInfo"/>
     <Platform Name="[^"]+"/>
   </Configurations>
-  <Project Path="ALL_BUILD\.vcxproj" Id="[0-9a-f-]+">
+  <Project Path="ALL_BUILD\.vcxproj" Id="[0-9a-f-]+" DefaultStartup="true">
     <BuildDependency Project="ZERO_CHECK\.vcxproj"/>
     <Build Solution="Debug\|\*" Project="false"/>
     <Build Solution="Release\|\*" Project="false"/>
diff --git a/Tests/RunCMake/VSSolution/OnePre-check-slnx.cmake b/Tests/RunCMake/VSSolution/OnePre-check-slnx.cmake
index e01b91a683..e6a1f7b686 100644
--- a/Tests/RunCMake/VSSolution/OnePre-check-slnx.cmake
+++ b/Tests/RunCMake/VSSolution/OnePre-check-slnx.cmake
@@ -8,7 +8,7 @@ RunCMake_check_slnx("${RunCMake_TEST_BINARY_DIR}/OnePre.slnx" [[
     <BuildType Name="RelWithDebInfo"/>
     <Platform Name="[^"]+"/>
   </Configurations>
-  <Project Path="ALL_BUILD\.vcxproj" Id="[0-9a-f-]+">
+  <Project Path="ALL_BUILD\.vcxproj" Id="[0-9a-f-]+" DefaultStartup="true">
     <BuildDependency Project="ZERO_CHECK\.vcxproj"/>
     <Build Solution="Debug\|\*" Project="false"/>
     <Build Solution="Release\|\*" Project="false"/>
diff --git a/Tests/RunCMake/VSSolution/Override1-check-slnx.cmake b/Tests/RunCMake/VSSolution/Override1-check-slnx.cmake
index 6b53eead35..a58bb01a2c 100644
--- a/Tests/RunCMake/VSSolution/Override1-check-slnx.cmake
+++ b/Tests/RunCMake/VSSolution/Override1-check-slnx.cmake
@@ -8,7 +8,7 @@ RunCMake_check_slnx("${RunCMake_TEST_BINARY_DIR}/Override1.slnx" [[
     <BuildType Name="RelWithDebInfo"/>
     <Platform Name="[^"]+"/>
   </Configurations>
-  <Project Path="ALL_BUILD\.vcxproj" Id="[0-9a-f-]+">
+  <Project Path="ALL_BUILD\.vcxproj" Id="[0-9a-f-]+" DefaultStartup="true">
     <BuildDependency Project="ZERO_CHECK\.vcxproj"/>
     <Build Solution="Debug\|\*" Project="false"/>
     <Build Solution="Release\|\*" Project="false"/>
diff --git a/Tests/RunCMake/VSSolution/Override2-check-slnx.cmake b/Tests/RunCMake/VSSolution/Override2-check-slnx.cmake
index 8a80a0ec44..b3b73f8318 100644
--- a/Tests/RunCMake/VSSolution/Override2-check-slnx.cmake
+++ b/Tests/RunCMake/VSSolution/Override2-check-slnx.cmake
@@ -8,7 +8,7 @@ RunCMake_check_slnx("${RunCMake_TEST_BINARY_DIR}/Override2.slnx" [[
     <BuildType Name="RelWithDebInfo"/>
     <Platform Name="[^"]+"/>
   </Configurations>
-  <Project Path="ALL_BUILD\.vcxproj" Id="[0-9a-f-]+">
+  <Project Path="ALL_BUILD\.vcxproj" Id="[0-9a-f-]+" DefaultStartup="true">
     <BuildDependency Project="ZERO_CHECK\.vcxproj"/>
     <Build Solution="Debug\|\*" Project="false"/>
     <Build Solution="Release\|\*" Project="false"/>
diff --git a/Tests/RunCMake/VSSolution/Override3-check-slnx.cmake b/Tests/RunCMake/VSSolution/Override3-check-slnx.cmake
index 93d6dc5e53..a756874afc 100644
--- a/Tests/RunCMake/VSSolution/Override3-check-slnx.cmake
+++ b/Tests/RunCMake/VSSolution/Override3-check-slnx.cmake
@@ -8,7 +8,7 @@ RunCMake_check_slnx("${RunCMake_TEST_BINARY_DIR}/Override3.slnx" [[
     <BuildType Name="RelWithDebInfo"/>
     <Platform Name="[^"]+"/>
   </Configurations>
-  <Project Path="ALL_BUILD\.vcxproj" Id="[0-9a-f-]+">
+  <Project Path="ALL_BUILD\.vcxproj" Id="[0-9a-f-]+" DefaultStartup="true">
     <BuildDependency Project="ZERO_CHECK\.vcxproj"/>
     <Build Solution="Debug\|\*" Project="false"/>
     <Build Solution="Release\|\*" Project="false"/>
diff --git a/Tests/RunCMake/VSSolution/PrePost-check-slnx.cmake b/Tests/RunCMake/VSSolution/PrePost-check-slnx.cmake
index 824add6565..f3f10c6c13 100644
--- a/Tests/RunCMake/VSSolution/PrePost-check-slnx.cmake
+++ b/Tests/RunCMake/VSSolution/PrePost-check-slnx.cmake
@@ -8,7 +8,7 @@ RunCMake_check_slnx("${RunCMake_TEST_BINARY_DIR}/PrePost.slnx" [[
     <BuildType Name="RelWithDebInfo"/>
     <Platform Name="[^"]+"/>
   </Configurations>
-  <Project Path="ALL_BUILD\.vcxproj" Id="[0-9a-f-]+">
+  <Project Path="ALL_BUILD\.vcxproj" Id="[0-9a-f-]+" DefaultStartup="true">
     <BuildDependency Project="ZERO_CHECK\.vcxproj"/>
     <Build Solution="Debug\|\*" Project="false"/>
     <Build Solution="Release\|\*" Project="false"/>
diff --git a/Tests/RunCMake/VSSolution/SolutionItems-check-slnx.cmake b/Tests/RunCMake/VSSolution/SolutionItems-check-slnx.cmake
index ee6f654b31..4021cbf411 100644
--- a/Tests/RunCMake/VSSolution/SolutionItems-check-slnx.cmake
+++ b/Tests/RunCMake/VSSolution/SolutionItems-check-slnx.cmake
@@ -8,7 +8,7 @@ RunCMake_check_slnx("${RunCMake_TEST_BINARY_DIR}/SolutionItems.slnx" [[
     <BuildType Name="RelWithDebInfo"/>
     <Platform Name="[^"]+"/>
   </Configurations>
-  <Project Path="ALL_BUILD\.vcxproj" Id="[0-9a-f-]+">
+  <Project Path="ALL_BUILD\.vcxproj" Id="[0-9a-f-]+" DefaultStartup="true">
     <BuildDependency Project="ZERO_CHECK\.vcxproj"/>
     <Build Solution="Debug\|\*" Project="false"/>
     <Build Solution="Release\|\*" Project="false"/>
@@ -38,7 +38,7 @@ RunCMake_check_slnx("${RunCMake_TEST_BINARY_DIR}/SolutionItems/SolutionItemsSubp
     <BuildType Name="RelWithDebInfo"/>
     <Platform Name="[^"]+"/>
   </Configurations>
-  <Project Path="ALL_BUILD\.vcxproj" Id="[0-9a-f-]+">
+  <Project Path="ALL_BUILD\.vcxproj" Id="[0-9a-f-]+" DefaultStartup="true">
     <BuildDependency Project="\.\./ZERO_CHECK\.vcxproj"/>
     <Build Solution="Debug\|\*" Project="false"/>
     <Build Solution="Release\|\*" Project="false"/>
diff --git a/Tests/RunCMake/VSSolution/StartupProject-check-slnx.cmake b/Tests/RunCMake/VSSolution/StartupProject-check-slnx.cmake
index efd6fcd6ab..b8f9639b59 100644
--- a/Tests/RunCMake/VSSolution/StartupProject-check-slnx.cmake
+++ b/Tests/RunCMake/VSSolution/StartupProject-check-slnx.cmake
@@ -15,7 +15,7 @@ RunCMake_check_slnx("${RunCMake_TEST_BINARY_DIR}/StartupProject.slnx" [[
     <Build Solution="MinSizeRel\|\*" Project="false"/>
     <Build Solution="RelWithDebInfo\|\*" Project="false"/>
   </Project>
-  <Project Path="TestStartup\.vcxproj" Id="[0-9a-f-]+">
+  <Project Path="TestStartup\.vcxproj" Id="[0-9a-f-]+" DefaultStartup="true">
     <BuildDependency Project="ZERO_CHECK\.vcxproj"/>
     <Build Solution="Debug\|\*" Project="false"/>
     <Build Solution="Release\|\*" Project="false"/>
diff --git a/Tests/RunCMake/VSSolution/StartupProjectMissing-check-slnx.cmake b/Tests/RunCMake/VSSolution/StartupProjectMissing-check-slnx.cmake
index f2de6f324c..ce0f3822d2 100644
--- a/Tests/RunCMake/VSSolution/StartupProjectMissing-check-slnx.cmake
+++ b/Tests/RunCMake/VSSolution/StartupProjectMissing-check-slnx.cmake
@@ -8,7 +8,7 @@ RunCMake_check_slnx("${RunCMake_TEST_BINARY_DIR}/StartupProjectMissing.slnx" [[
     <BuildType Name="RelWithDebInfo"/>
     <Platform Name="[^"]+"/>
   </Configurations>
-  <Project Path="ALL_BUILD\.vcxproj" Id="[0-9a-f-]+">
+  <Project Path="ALL_BUILD\.vcxproj" Id="[0-9a-f-]+" DefaultStartup="true">
     <BuildDependency Project="ZERO_CHECK\.vcxproj"/>
     <Build Solution="Debug\|\*" Project="false"/>
     <Build Solution="Release\|\*" Project="false"/>
diff --git a/Tests/RunCMake/VSSolution/StartupProjectUseFolders-check-slnx.cmake b/Tests/RunCMake/VSSolution/StartupProjectUseFolders-check-slnx.cmake
index dcebe09298..c3aef00aa7 100644
--- a/Tests/RunCMake/VSSolution/StartupProjectUseFolders-check-slnx.cmake
+++ b/Tests/RunCMake/VSSolution/StartupProjectUseFolders-check-slnx.cmake
@@ -8,7 +8,7 @@ RunCMake_check_slnx("${RunCMake_TEST_BINARY_DIR}/StartupProjectUseFolders.slnx"
     <BuildType Name="RelWithDebInfo"/>
     <Platform Name="[^"]+"/>
   </Configurations>
-  <Project Path="TestStartup\.vcxproj" Id="[0-9a-f-]+">
+  <Project Path="TestStartup\.vcxproj" Id="[0-9a-f-]+" DefaultStartup="true">
     <BuildDependency Project="ZERO_CHECK.vcxproj"/>
     <Build Solution="Debug\|\*" Project="false"/>
     <Build Solution="Release\|\*" Project="false"/>
diff --git a/Tests/RunCMake/VsDotnetSdk/VsDotnetSdkTargetPlatform-check-slnx.cmake b/Tests/RunCMake/VsDotnetSdk/VsDotnetSdkTargetPlatform-check-slnx.cmake
index f1f7492c1c..aa1c0f60c8 100644
--- a/Tests/RunCMake/VsDotnetSdk/VsDotnetSdkTargetPlatform-check-slnx.cmake
+++ b/Tests/RunCMake/VsDotnetSdk/VsDotnetSdkTargetPlatform-check-slnx.cmake
@@ -8,7 +8,7 @@ RunCMake_check_slnx("${RunCMake_TEST_BINARY_DIR}/VsDotnetSdkTargetPlatform.slnx"
     <BuildType Name="RelWithDebInfo"/>
     <Platform Name="[^"]+"/>
   </Configurations>
-  <Project Path="ALL_BUILD\.vcxproj" Id="[0-9a-f-]+">
+  <Project Path="ALL_BUILD\.vcxproj" Id="[0-9a-f-]+" DefaultStartup="true">
     <BuildDependency Project="ZERO_CHECK\.vcxproj"/>
     <BuildDependency Project="foo\.csproj"/>
     <Build Solution="Debug\|\*" Project="false"/>
diff --git a/Tests/RunCMake/include_external_msproject/AutoType-check-slnx.cmake b/Tests/RunCMake/include_external_msproject/AutoType-check-slnx.cmake
index 560c9c0229..ba6894161f 100644
--- a/Tests/RunCMake/include_external_msproject/AutoType-check-slnx.cmake
+++ b/Tests/RunCMake/include_external_msproject/AutoType-check-slnx.cmake
@@ -8,7 +8,7 @@ RunCMake_check_slnx("${RunCMake_TEST_BINARY_DIR}/AutoType.slnx" [[
     <BuildType Name="RelWithDebInfo"/>
     <Platform Name="[^"]+"/>
   </Configurations>
-  <Project Path="ALL_BUILD\.vcxproj" Id="[0-9a-f-]+">
+  <Project Path="ALL_BUILD\.vcxproj" Id="[0-9a-f-]+" DefaultStartup="true">
     <BuildDependency Project="ZERO_CHECK\.vcxproj"/>
     <BuildDependency Project="external\.csproj"/>
     <BuildDependency Project="external\.dbproj"/>
diff --git a/Tests/RunCMake/include_external_msproject/CustomConfig-check-slnx.cmake b/Tests/RunCMake/include_external_msproject/CustomConfig-check-slnx.cmake
index 439d9ffb66..d3f5b8b064 100644
--- a/Tests/RunCMake/include_external_msproject/CustomConfig-check-slnx.cmake
+++ b/Tests/RunCMake/include_external_msproject/CustomConfig-check-slnx.cmake
@@ -8,7 +8,7 @@ RunCMake_check_slnx("${RunCMake_TEST_BINARY_DIR}/CustomConfig.slnx" [[
     <BuildType Name="RelWithDebInfo"/>
     <Platform Name="[^"]+"/>
   </Configurations>
-  <Project Path="ALL_BUILD\.vcxproj" Id="[0-9a-f-]+">
+  <Project Path="ALL_BUILD\.vcxproj" Id="[0-9a-f-]+" DefaultStartup="true">
     <BuildDependency Project="ZERO_CHECK\.vcxproj"/>
     <BuildDependency Project="external.project"/>
     <Build Solution="Debug\|\*" Project="false"/>
diff --git a/Tests/RunCMake/include_external_msproject/CustomGuid-check-slnx.cmake b/Tests/RunCMake/include_external_msproject/CustomGuid-check-slnx.cmake
index c03a4280f8..07a16b61a0 100644
--- a/Tests/RunCMake/include_external_msproject/CustomGuid-check-slnx.cmake
+++ b/Tests/RunCMake/include_external_msproject/CustomGuid-check-slnx.cmake
@@ -8,7 +8,7 @@ RunCMake_check_slnx("${RunCMake_TEST_BINARY_DIR}/CustomGuid.slnx" [[
     <BuildType Name="RelWithDebInfo"/>
     <Platform Name="[^"]+"/>
   </Configurations>
-  <Project Path="ALL_BUILD\.vcxproj" Id="[0-9a-f-]+">
+  <Project Path="ALL_BUILD\.vcxproj" Id="[0-9a-f-]+" DefaultStartup="true">
     <BuildDependency Project="ZERO_CHECK\.vcxproj"/>
     <BuildDependency Project="external.project"/>
     <Build Solution="Debug\|\*" Project="false"/>
diff --git a/Tests/RunCMake/include_external_msproject/CustomGuidTypePlatform-check-slnx.cmake b/Tests/RunCMake/include_external_msproject/CustomGuidTypePlatform-check-slnx.cmake
index 9792fde7ec..a5806d03f2 100644
--- a/Tests/RunCMake/include_external_msproject/CustomGuidTypePlatform-check-slnx.cmake
+++ b/Tests/RunCMake/include_external_msproject/CustomGuidTypePlatform-check-slnx.cmake
@@ -8,7 +8,7 @@ RunCMake_check_slnx("${RunCMake_TEST_BINARY_DIR}/CustomGuidTypePlatform.slnx" [[
     <BuildType Name="RelWithDebInfo"/>
     <Platform Name="[^"]+"/>
   </Configurations>
-  <Project Path="ALL_BUILD\.vcxproj" Id="[0-9a-f-]+">
+  <Project Path="ALL_BUILD\.vcxproj" Id="[0-9a-f-]+" DefaultStartup="true">
     <BuildDependency Project="ZERO_CHECK\.vcxproj"/>
     <BuildDependency Project="external.project"/>
     <Build Solution="Debug\|\*" Project="false"/>
diff --git a/Tests/RunCMake/include_external_msproject/CustomTypePlatform-check-slnx.cmake b/Tests/RunCMake/include_external_msproject/CustomTypePlatform-check-slnx.cmake
index 30156f1542..5eb662275a 100644
--- a/Tests/RunCMake/include_external_msproject/CustomTypePlatform-check-slnx.cmake
+++ b/Tests/RunCMake/include_external_msproject/CustomTypePlatform-check-slnx.cmake
@@ -8,7 +8,7 @@ RunCMake_check_slnx("${RunCMake_TEST_BINARY_DIR}/CustomTypePlatform.slnx" [[
     <BuildType Name="RelWithDebInfo"/>
     <Platform Name="[^"]+"/>
   </Configurations>
-  <Project Path="ALL_BUILD\.vcxproj" Id="[0-9a-f-]+">
+  <Project Path="ALL_BUILD\.vcxproj" Id="[0-9a-f-]+" DefaultStartup="true">
     <BuildDependency Project="ZERO_CHECK\.vcxproj"/>
     <BuildDependency Project="external.project"/>
     <Build Solution="Debug\|\*" Project="false"/>