diff --git a/lib/csharp/ThriftMSBuildTask/ThriftBuild.cs b/lib/csharp/ThriftMSBuildTask/ThriftBuild.cs
index 4389e0a..75bb339 100644
--- a/lib/csharp/ThriftMSBuildTask/ThriftBuild.cs
+++ b/lib/csharp/ThriftMSBuildTask/ThriftBuild.cs
@@ -15,6 +15,10 @@
  * KIND, either express or implied. See the License for the
  * specific language governing permissions and limitations
  * under the License.
+ *
+ * Contains some contributions under the Thrift Software License.
+ * Please see doc/old-thrift-license.txt in the Thrift distribution for
+ * details.
  */
 
 using System;