diff --git a/src/Tasks/Microsoft.NET.Build.Tasks/ClsidMap.cs b/src/Tasks/Microsoft.NET.Build.Tasks/ClsidMap.cs
index 8075190cf419..141d0d3134f4 100644
--- a/src/Tasks/Microsoft.NET.Build.Tasks/ClsidMap.cs
+++ b/src/Tasks/Microsoft.NET.Build.Tasks/ClsidMap.cs
@@ -39,7 +39,7 @@ public static void Create(MetadataReader metadataReader, string clsidMapPath)
                 // Only public COM-visible classes can be exposed via the COM host.
                 if (TypeIsPublic(metadataReader, definition) && TypeIsClass(metadataReader, definition) && IsComVisible(metadataReader, definition, isAssemblyComVisible))
                 {
-                    string guid = GetTypeGuid(metadataReader, definition);
+                    string guid = GetTypeGuid(metadataReader, definition).ToString("B");
 
                     if (clsidMap.ContainsKey(guid))
                     {
@@ -177,7 +177,7 @@ private static CustomAttributeHandle GetComVisibleAttribute(MetadataReader reade
             return new CustomAttributeHandle();
         }
 
-        private static string GetTypeGuid(MetadataReader reader, TypeDefinition type)
+        private static Guid GetTypeGuid(MetadataReader reader, TypeDefinition type)
         {
             // Find the class' GUID by reading the GuidAttribute value.
             // We do not support implicit runtime-generated GUIDs for the .NET Core COM host.
@@ -189,7 +189,7 @@ private static string GetTypeGuid(MetadataReader reader, TypeDefinition type)
                 if (reader.StringComparer.Equals(attributeType.Namespace, "System.Runtime.InteropServices") && reader.StringComparer.Equals(attributeType.Name, "GuidAttribute"))
                 {
                     CustomAttributeValue<KnownType> data = attribute.DecodeValue(new TypeResolver());
-                    return (string)data.FixedArguments[0].Value;
+                    return Guid.Parse((string)data.FixedArguments[0].Value);
                 }
             }
             throw new BuildErrorException(Strings.ClsidMapExportedTypesRequireExplicitGuid, GetTypeName(reader, type));
diff --git a/src/Tasks/Microsoft.NET.Build.Tasks/RegFreeComManifest.cs b/src/Tasks/Microsoft.NET.Build.Tasks/RegFreeComManifest.cs
index 65bec4e7f946..8e2b8ff2e4bb 100644
--- a/src/Tasks/Microsoft.NET.Build.Tasks/RegFreeComManifest.cs
+++ b/src/Tasks/Microsoft.NET.Build.Tasks/RegFreeComManifest.cs
@@ -20,13 +20,13 @@ internal static class RegFreeComManifest
         /// <param name="assemblyName">The name of the assembly.</param>
         /// <param name="comHostName">The name of the comhost library.</param>
         /// <param name="assemblyVersion">The version of the assembly.</param>
-        /// <param name="clsidMapPath">The path to the clasidmap file.</param>
+        /// <param name="clsidMapPath">The path to the clsidmap file.</param>
         /// <param name="comManifestPath">The path to which to write the manifest.</param>
         public static void CreateManifestFromClsidmap(string assemblyName, string comHostName, string assemblyVersion, string clsidMapPath, string comManifestPath)
         {
-            XNamespace ns = "urn:shemas-microsoft-com:asm.v1";
+            XNamespace ns = "urn:schemas-microsoft-com:asm.v1";
 
-            XElement manifest = new XElement(ns + "assembly", new XAttribute("mainfestVersion", "1.0"));
+            XElement manifest = new XElement(ns + "assembly", new XAttribute("manifestVersion", "1.0"));
             manifest.Add(new XElement(ns + "assemblyIdentity",
                 new XAttribute("type", "win32"),
                 new XAttribute("name", $"{assemblyName}.X"),
@@ -44,14 +44,19 @@ public static void CreateManifestFromClsidmap(string assemblyName, string comHos
 
             foreach (JProperty property in clsidMap.Properties())
             {
-                string guid = property.Name;
-                fileElement.Add(new XElement(ns + "comClass", new XAttribute("clsid", guid), new XAttribute("threadingModel", "Both")));
+                string guidMaybe = property.Name;
+                Guid guid = Guid.Parse(guidMaybe);
+                fileElement.Add(new XElement(ns + "comClass", new XAttribute("clsid", guid.ToString("B")), new XAttribute("threadingModel", "Both")));
             }
 
             manifest.Add(fileElement);
 
             XDocument manifestDocument = new XDocument(new XDeclaration("1.0", "UTF-8", "yes"), manifest);
-            using (XmlWriter manifestWriter = XmlWriter.Create(comManifestPath))
+            XmlWriterSettings settings = new XmlWriterSettings()
+            {
+                Encoding = new UTF8Encoding(encoderShouldEmitUTF8Identifier: false)
+            };
+            using (XmlWriter manifestWriter = XmlWriter.Create(comManifestPath, settings))
             {
                 manifestDocument.WriteTo(manifestWriter);
             }