diff --git a/modules/openapi-generator/src/main/resources/csharp-netcore/libraries/httpclient/ApiClient.mustache b/modules/openapi-generator/src/main/resources/csharp-netcore/libraries/httpclient/ApiClient.mustache
index c94d7aaeae6..bd7663012f1 100644
--- a/modules/openapi-generator/src/main/resources/csharp-netcore/libraries/httpclient/ApiClient.mustache
+++ b/modules/openapi-generator/src/main/resources/csharp-netcore/libraries/httpclient/ApiClient.mustache
@@ -279,7 +279,7 @@ namespace {{packageName}}.Client
                 foreach (var fileParam in options.FileParameters)
                 {
                     var content = new StreamContent(fileParam.Value.Content);
-                    content.Headers.ContentType = new MediaTypeHeaderValue("application/octet-stream");
+                    content.Headers.ContentType = new MediaTypeHeaderValue(fileParam.Value.ContentType);
                     multipartContent.Add(content, fileParam.Key,
                         fileParam.Value.Name);
                 }
diff --git a/modules/openapi-generator/src/main/resources/csharp-netcore/libraries/httpclient/FileParameter.mustache b/modules/openapi-generator/src/main/resources/csharp-netcore/libraries/httpclient/FileParameter.mustache
index 3fa243ed54f..87e5fcdc9af 100644
--- a/modules/openapi-generator/src/main/resources/csharp-netcore/libraries/httpclient/FileParameter.mustache
+++ b/modules/openapi-generator/src/main/resources/csharp-netcore/libraries/httpclient/FileParameter.mustache
@@ -15,6 +15,11 @@ namespace {{packageName}}.Client
         /// </summary>
         public string Name { get; set; } = "no_name_provided";
 
+        /// <summary>
+        /// The content type of the file
+        /// </summary>
+        public string ContentType { get; set; } = "application/octet-stream";
+
         /// <summary>
         /// The content of the file
         /// </summary>
@@ -44,6 +49,19 @@ namespace {{packageName}}.Client
             Content = content;
         }
 
+        /// <summary>
+        /// Construct a FileParameter from name and content
+        /// </summary>
+        /// <param name="filename">The filename</param>
+        /// <param name="contentType">The content type of the file</param>
+        /// <param name="content">The file content</param>
+        public FileParameter(string filename, string contentType, Stream content)
+        {
+            Name = filename;
+            ContentType = contentType;
+            Content = content;
+        }
+
         /// <summary>
         /// Implicit conversion of stream to file parameter. Useful for backwards compatibility.
         /// </summary>
diff --git a/samples/client/petstore/csharp-netcore/OpenAPIClient-httpclient/src/Org.OpenAPITools/Client/ApiClient.cs b/samples/client/petstore/csharp-netcore/OpenAPIClient-httpclient/src/Org.OpenAPITools/Client/ApiClient.cs
index 4ef5e9ead3b..b6d9195b3f6 100644
--- a/samples/client/petstore/csharp-netcore/OpenAPIClient-httpclient/src/Org.OpenAPITools/Client/ApiClient.cs
+++ b/samples/client/petstore/csharp-netcore/OpenAPIClient-httpclient/src/Org.OpenAPITools/Client/ApiClient.cs
@@ -278,7 +278,7 @@ namespace Org.OpenAPITools.Client
                 foreach (var fileParam in options.FileParameters)
                 {
                     var content = new StreamContent(fileParam.Value.Content);
-                    content.Headers.ContentType = new MediaTypeHeaderValue("application/octet-stream");
+                    content.Headers.ContentType = new MediaTypeHeaderValue(fileParam.Value.ContentType);
                     multipartContent.Add(content, fileParam.Key,
                         fileParam.Value.Name);
                 }
diff --git a/samples/client/petstore/csharp-netcore/OpenAPIClient-httpclient/src/Org.OpenAPITools/Client/FileParameter.cs b/samples/client/petstore/csharp-netcore/OpenAPIClient-httpclient/src/Org.OpenAPITools/Client/FileParameter.cs
index 4a83ada8588..6d173fe9b3b 100644
--- a/samples/client/petstore/csharp-netcore/OpenAPIClient-httpclient/src/Org.OpenAPITools/Client/FileParameter.cs
+++ b/samples/client/petstore/csharp-netcore/OpenAPIClient-httpclient/src/Org.OpenAPITools/Client/FileParameter.cs
@@ -23,6 +23,11 @@ namespace Org.OpenAPITools.Client
         /// </summary>
         public string Name { get; set; } = "no_name_provided";
 
+        /// <summary>
+        /// The content type of the file
+        /// </summary>
+        public string ContentType { get; set; } = "application/octet-stream";
+
         /// <summary>
         /// The content of the file
         /// </summary>
@@ -52,6 +57,19 @@ namespace Org.OpenAPITools.Client
             Content = content;
         }
 
+        /// <summary>
+        /// Construct a FileParameter from name and content
+        /// </summary>
+        /// <param name="filename">The filename</param>
+        /// <param name="contentType">The content type of the file</param>
+        /// <param name="content">The file content</param>
+        public FileParameter(string filename, string contentType, Stream content)
+        {
+            Name = filename;
+            ContentType = contentType;
+            Content = content;
+        }
+
         /// <summary>
         /// Implicit conversion of stream to file parameter. Useful for backwards compatibility.
         /// </summary>