diff --git a/modules/swagger-codegen/src/main/resources/csharp/ApiClient.mustache b/modules/swagger-codegen/src/main/resources/csharp/ApiClient.mustache
index 84ff68ffbbe..158d087140b 100644
--- a/modules/swagger-codegen/src/main/resources/csharp/ApiClient.mustache
+++ b/modules/swagger-codegen/src/main/resources/csharp/ApiClient.mustache
@@ -116,7 +116,7 @@ namespace {{packageName}}.Client
 
         // Creates and sets up a RestRequest prior to a call.
         private RestRequest PrepareRequest(
-            String path, {{^netStandard}}RestSharp.{{/netStandard}}Method method, Dictionary<String, String> queryParams, Object postBody,
+            String path, {{^netStandard}}RestSharp.{{/netStandard}}Method method, List<KeyValuePair<String, String>> queryParams, Object postBody,
             Dictionary<String, String> headerParams, Dictionary<String, String> formParams,
             Dictionary<String, FileParameter> fileParams, Dictionary<String, String> pathParams,
             String contentType)
diff --git a/samples/client/petstore/csharp/SwaggerClient.v5/src/IO.Swagger/Client/ApiClient.cs b/samples/client/petstore/csharp/SwaggerClient.v5/src/IO.Swagger/Client/ApiClient.cs
index 9ac801f8191..f1d2250b4fc 100644
--- a/samples/client/petstore/csharp/SwaggerClient.v5/src/IO.Swagger/Client/ApiClient.cs
+++ b/samples/client/petstore/csharp/SwaggerClient.v5/src/IO.Swagger/Client/ApiClient.cs
@@ -109,7 +109,7 @@ namespace IO.Swagger.Client
 
         // Creates and sets up a RestRequest prior to a call.
         private RestRequest PrepareRequest(
-            String path, Method method, Dictionary<String, String> queryParams, Object postBody,
+            String path, Method method, List<KeyValuePair<String, String>> queryParams, Object postBody,
             Dictionary<String, String> headerParams, Dictionary<String, String> formParams,
             Dictionary<String, FileParameter> fileParams, Dictionary<String, String> pathParams,
             String contentType)
diff --git a/samples/client/petstore/csharp/SwaggerClient/src/IO.Swagger/Client/ApiClient.cs b/samples/client/petstore/csharp/SwaggerClient/src/IO.Swagger/Client/ApiClient.cs
index 20aa1836ceb..7bed82dbcc3 100644
--- a/samples/client/petstore/csharp/SwaggerClient/src/IO.Swagger/Client/ApiClient.cs
+++ b/samples/client/petstore/csharp/SwaggerClient/src/IO.Swagger/Client/ApiClient.cs
@@ -106,7 +106,7 @@ namespace IO.Swagger.Client
 
         // Creates and sets up a RestRequest prior to a call.
         private RestRequest PrepareRequest(
-            String path, RestSharp.Method method, Dictionary<String, String> queryParams, Object postBody,
+            String path, RestSharp.Method method, List<KeyValuePair<String, String>> queryParams, Object postBody,
             Dictionary<String, String> headerParams, Dictionary<String, String> formParams,
             Dictionary<String, FileParameter> fileParams, Dictionary<String, String> pathParams,
             String contentType)
diff --git a/samples/client/petstore/csharp/SwaggerClientWithPropertyChanged/src/IO.Swagger/Client/ApiClient.cs b/samples/client/petstore/csharp/SwaggerClientWithPropertyChanged/src/IO.Swagger/Client/ApiClient.cs
index 20aa1836ceb..7bed82dbcc3 100644
--- a/samples/client/petstore/csharp/SwaggerClientWithPropertyChanged/src/IO.Swagger/Client/ApiClient.cs
+++ b/samples/client/petstore/csharp/SwaggerClientWithPropertyChanged/src/IO.Swagger/Client/ApiClient.cs
@@ -106,7 +106,7 @@ namespace IO.Swagger.Client
 
         // Creates and sets up a RestRequest prior to a call.
         private RestRequest PrepareRequest(
-            String path, RestSharp.Method method, Dictionary<String, String> queryParams, Object postBody,
+            String path, RestSharp.Method method, List<KeyValuePair<String, String>> queryParams, Object postBody,
             Dictionary<String, String> headerParams, Dictionary<String, String> formParams,
             Dictionary<String, FileParameter> fileParams, Dictionary<String, String> pathParams,
             String contentType)