diff --git a/modules/swagger-codegen/src/main/resources/csharp/ApiClient.mustache b/modules/swagger-codegen/src/main/resources/csharp/ApiClient.mustache
index 45316e679fa..f7ebba9942f 100644
--- a/modules/swagger-codegen/src/main/resources/csharp/ApiClient.mustache
+++ b/modules/swagger-codegen/src/main/resources/csharp/ApiClient.mustache
@@ -162,7 +162,7 @@ namespace {{packageName}}.Client
         /// <returns>Escaped string.</returns>
         public string EscapeString(string str)
         {
-            return HttpUtility.UrlEncode(str);
+            return RestSharp.Contrib.HttpUtility.UrlEncode(str);
         }
     
         /// <summary>
diff --git a/samples/client/petstore/csharp/SwaggerClientTest/Lib/SwaggerClient/src/main/csharp/IO/Swagger/Client/ApiClient.cs b/samples/client/petstore/csharp/SwaggerClientTest/Lib/SwaggerClient/src/main/csharp/IO/Swagger/Client/ApiClient.cs
index 117cd598008..803e7dafa5d 100644
--- a/samples/client/petstore/csharp/SwaggerClientTest/Lib/SwaggerClient/src/main/csharp/IO/Swagger/Client/ApiClient.cs
+++ b/samples/client/petstore/csharp/SwaggerClientTest/Lib/SwaggerClient/src/main/csharp/IO/Swagger/Client/ApiClient.cs
@@ -162,7 +162,7 @@ namespace IO.Swagger.Client
         /// <returns>Escaped string.</returns>
         public string EscapeString(string str)
         {
-            return HttpUtility.UrlEncode(str);
+            return RestSharp.Contrib.HttpUtility.UrlEncode(str);
         }
     
         /// <summary>