diff --git a/modules/swagger-codegen/src/main/resources/csharp/model.mustache b/modules/swagger-codegen/src/main/resources/csharp/model.mustache
index 99da4f8302..d40ece4cc0 100644
--- a/modules/swagger-codegen/src/main/resources/csharp/model.mustache
+++ b/modules/swagger-codegen/src/main/resources/csharp/model.mustache
@@ -1,4 +1,5 @@
 using System;
+using System.IO;
 using System.Text;
 using System.Collections;
 using System.Collections.Generic;
diff --git a/samples/client/petstore/csharp/SwaggerClientTest/Lib/SwaggerClient/src/main/csharp/IO/Swagger/Model/Category.cs b/samples/client/petstore/csharp/SwaggerClientTest/Lib/SwaggerClient/src/main/csharp/IO/Swagger/Model/Category.cs
index c402188b9f..56ebfdb3b7 100644
--- a/samples/client/petstore/csharp/SwaggerClientTest/Lib/SwaggerClient/src/main/csharp/IO/Swagger/Model/Category.cs
+++ b/samples/client/petstore/csharp/SwaggerClientTest/Lib/SwaggerClient/src/main/csharp/IO/Swagger/Model/Category.cs
@@ -1,4 +1,5 @@
 using System;
+using System.IO;
 using System.Text;
 using System.Collections;
 using System.Collections.Generic;
diff --git a/samples/client/petstore/csharp/SwaggerClientTest/Lib/SwaggerClient/src/main/csharp/IO/Swagger/Model/Order.cs b/samples/client/petstore/csharp/SwaggerClientTest/Lib/SwaggerClient/src/main/csharp/IO/Swagger/Model/Order.cs
index 07b3d14e59..1fa62c1605 100644
--- a/samples/client/petstore/csharp/SwaggerClientTest/Lib/SwaggerClient/src/main/csharp/IO/Swagger/Model/Order.cs
+++ b/samples/client/petstore/csharp/SwaggerClientTest/Lib/SwaggerClient/src/main/csharp/IO/Swagger/Model/Order.cs
@@ -1,4 +1,5 @@
 using System;
+using System.IO;
 using System.Text;
 using System.Collections;
 using System.Collections.Generic;
diff --git a/samples/client/petstore/csharp/SwaggerClientTest/Lib/SwaggerClient/src/main/csharp/IO/Swagger/Model/Pet.cs b/samples/client/petstore/csharp/SwaggerClientTest/Lib/SwaggerClient/src/main/csharp/IO/Swagger/Model/Pet.cs
index 41216b5280..37c8025994 100644
--- a/samples/client/petstore/csharp/SwaggerClientTest/Lib/SwaggerClient/src/main/csharp/IO/Swagger/Model/Pet.cs
+++ b/samples/client/petstore/csharp/SwaggerClientTest/Lib/SwaggerClient/src/main/csharp/IO/Swagger/Model/Pet.cs
@@ -1,4 +1,5 @@
 using System;
+using System.IO;
 using System.Text;
 using System.Collections;
 using System.Collections.Generic;
diff --git a/samples/client/petstore/csharp/SwaggerClientTest/Lib/SwaggerClient/src/main/csharp/IO/Swagger/Model/Tag.cs b/samples/client/petstore/csharp/SwaggerClientTest/Lib/SwaggerClient/src/main/csharp/IO/Swagger/Model/Tag.cs
index 10ace1ad18..7d2ea38833 100644
--- a/samples/client/petstore/csharp/SwaggerClientTest/Lib/SwaggerClient/src/main/csharp/IO/Swagger/Model/Tag.cs
+++ b/samples/client/petstore/csharp/SwaggerClientTest/Lib/SwaggerClient/src/main/csharp/IO/Swagger/Model/Tag.cs
@@ -1,4 +1,5 @@
 using System;
+using System.IO;
 using System.Text;
 using System.Collections;
 using System.Collections.Generic;
diff --git a/samples/client/petstore/csharp/SwaggerClientTest/Lib/SwaggerClient/src/main/csharp/IO/Swagger/Model/User.cs b/samples/client/petstore/csharp/SwaggerClientTest/Lib/SwaggerClient/src/main/csharp/IO/Swagger/Model/User.cs
index d22ac54c09..5430d1182c 100644
--- a/samples/client/petstore/csharp/SwaggerClientTest/Lib/SwaggerClient/src/main/csharp/IO/Swagger/Model/User.cs
+++ b/samples/client/petstore/csharp/SwaggerClientTest/Lib/SwaggerClient/src/main/csharp/IO/Swagger/Model/User.cs
@@ -1,4 +1,5 @@
 using System;
+using System.IO;
 using System.Text;
 using System.Collections;
 using System.Collections.Generic;
diff --git a/samples/client/petstore/csharp/SwaggerClientTest/bin/Debug/SwaggerClientTest.dll.mdb b/samples/client/petstore/csharp/SwaggerClientTest/bin/Debug/SwaggerClientTest.dll.mdb
index 1a9c96751b..f63c1d21fe 100644
Binary files a/samples/client/petstore/csharp/SwaggerClientTest/bin/Debug/SwaggerClientTest.dll.mdb and b/samples/client/petstore/csharp/SwaggerClientTest/bin/Debug/SwaggerClientTest.dll.mdb differ
diff --git a/samples/client/petstore/csharp/SwaggerClientTest/obj/Debug/SwaggerClientTest.dll.mdb b/samples/client/petstore/csharp/SwaggerClientTest/obj/Debug/SwaggerClientTest.dll.mdb
index 1a9c96751b..f63c1d21fe 100644
Binary files a/samples/client/petstore/csharp/SwaggerClientTest/obj/Debug/SwaggerClientTest.dll.mdb and b/samples/client/petstore/csharp/SwaggerClientTest/obj/Debug/SwaggerClientTest.dll.mdb differ