diff --git a/modules/openapi-generator/src/main/resources/csharp/libraries/httpclient/ApiClient.mustache b/modules/openapi-generator/src/main/resources/csharp/libraries/httpclient/ApiClient.mustache
index 021fcb79a383..22993e54336c 100644
--- a/modules/openapi-generator/src/main/resources/csharp/libraries/httpclient/ApiClient.mustache
+++ b/modules/openapi-generator/src/main/resources/csharp/libraries/httpclient/ApiClient.mustache
@@ -91,7 +91,18 @@ namespace {{packageName}}.Client
         /// <returns>Object representation of the JSON string.</returns>
         internal async Task<object> Deserialize(HttpResponseMessage response, Type type)
         {
-            IList<string> headers = response.Headers.Select(x => x.Key + "=" + x.Value).ToList();
+            IList<string> headers = new List<string>();
+            // process response headers, e.g. Access-Control-Allow-Methods
+            foreach (var responseHeader in response.Headers)
+            {
+                headers.Add(responseHeader.Key + "=" +  ClientUtils.ParameterToString(responseHeader.Value));
+            }
+
+            // process response content headers, e.g. Content-Type
+            foreach (var responseHeader in response.Content.Headers)
+            {
+                headers.Add(responseHeader.Key + "=" +  ClientUtils.ParameterToString(responseHeader.Value));
+            }
 
             if (type == typeof(byte[])) // return byte array
             {
diff --git a/samples/client/petstore/csharp/OpenAPIClient-httpclient/src/Org.OpenAPITools/Client/ApiClient.cs b/samples/client/petstore/csharp/OpenAPIClient-httpclient/src/Org.OpenAPITools/Client/ApiClient.cs
index f6e3372563a8..b814e218a612 100644
--- a/samples/client/petstore/csharp/OpenAPIClient-httpclient/src/Org.OpenAPITools/Client/ApiClient.cs
+++ b/samples/client/petstore/csharp/OpenAPIClient-httpclient/src/Org.OpenAPITools/Client/ApiClient.cs
@@ -94,7 +94,18 @@ public async Task<T> Deserialize<T>(HttpResponseMessage response)
         /// <returns>Object representation of the JSON string.</returns>
         internal async Task<object> Deserialize(HttpResponseMessage response, Type type)
         {
-            IList<string> headers = response.Headers.Select(x => x.Key + "=" + x.Value).ToList();
+            IList<string> headers = new List<string>();
+            // process response headers, e.g. Access-Control-Allow-Methods
+            foreach (var responseHeader in response.Headers)
+            {
+                headers.Add(responseHeader.Key + "=" +  ClientUtils.ParameterToString(responseHeader.Value));
+            }
+
+            // process response content headers, e.g. Content-Type
+            foreach (var responseHeader in response.Content.Headers)
+            {
+                headers.Add(responseHeader.Key + "=" +  ClientUtils.ParameterToString(responseHeader.Value));
+            }
 
             if (type == typeof(byte[])) // return byte array
             {