diff --git a/src/Tasks/CombineTargetFrameworkInfoProperties.cs b/src/Tasks/CombineTargetFrameworkInfoProperties.cs
index 7506fbc8be0..e2a2f6baa37 100644
--- a/src/Tasks/CombineTargetFrameworkInfoProperties.cs
+++ b/src/Tasks/CombineTargetFrameworkInfoProperties.cs
@@ -12,6 +12,7 @@ namespace Microsoft.Build.Tasks
     /// <summary>
     /// Combines items that represent properties and values into an XML representation.
     /// </summary>
+    [MSBuildMultiThreadableTask]
     public class CombineTargetFrameworkInfoProperties : TaskExtension
     {
         /// <summary>
diff --git a/src/Tasks/CombineXmlElements.cs b/src/Tasks/CombineXmlElements.cs
index 8fb5af15dc2..04b973b4e79 100644
--- a/src/Tasks/CombineXmlElements.cs
+++ b/src/Tasks/CombineXmlElements.cs
@@ -11,6 +11,7 @@ namespace Microsoft.Build.Tasks
     /// <summary>
     /// Combines multiple XML elements
     /// </summary>
+    [MSBuildMultiThreadableTask]
     public class CombineXmlElements : TaskExtension
     {
         /// <summary>
diff --git a/src/Tasks/ErrorFromResources.cs b/src/Tasks/ErrorFromResources.cs
index a95a8ca2fd6..f931c5ebd15 100644
--- a/src/Tasks/ErrorFromResources.cs
+++ b/src/Tasks/ErrorFromResources.cs
@@ -13,6 +13,7 @@ namespace Microsoft.Build.Tasks
     /// Task that emits an error given a resource string. Engine will add project file path and line/column
     /// information.
     /// </summary>
+    [MSBuildMultiThreadableTask]
     public sealed class ErrorFromResources : TaskExtension
     {
         /// <summary>
diff --git a/src/Tasks/FindAppConfigFile.cs b/src/Tasks/FindAppConfigFile.cs
index f8b1332e062..656a5308db0 100644
--- a/src/Tasks/FindAppConfigFile.cs
+++ b/src/Tasks/FindAppConfigFile.cs
@@ -15,6 +15,7 @@ namespace Microsoft.Build.Tasks
     /// For compat reasons, it has to follow a particular arbitrary algorithm.
     /// It also adds the TargetPath metadata.
     /// </summary>
+    [MSBuildMultiThreadableTask]
     public class FindAppConfigFile : TaskExtension
     {
         // The list to search through
diff --git a/src/Tasks/FindInvalidProjectReferences.cs b/src/Tasks/FindInvalidProjectReferences.cs
index 607df8b83cd..7c2359a9e45 100644
--- a/src/Tasks/FindInvalidProjectReferences.cs
+++ b/src/Tasks/FindInvalidProjectReferences.cs
@@ -13,6 +13,7 @@ namespace Microsoft.Build.Tasks
     /// <summary>
     /// Returns the reference assembly paths to the various frameworks
     /// </summary>
+    [MSBuildMultiThreadableTask]
     public partial class FindInvalidProjectReferences : TaskExtension
     {
         #region Fields
diff --git a/src/Tasks/GetCompatiblePlatform.cs b/src/Tasks/GetCompatiblePlatform.cs
index c66e8542878..802a264331d 100644
--- a/src/Tasks/GetCompatiblePlatform.cs
+++ b/src/Tasks/GetCompatiblePlatform.cs
@@ -14,6 +14,7 @@ namespace Microsoft.Build.Tasks
     ///
     /// See ProjectReference-Protocol.md for details.
     /// </summary>
+    [MSBuildMultiThreadableTask]
     public class GetCompatiblePlatform : TaskExtension
     {
         /// <summary>