diff --git a/src/NSwag.CodeGeneration.CSharp.Tests/BinaryTests.cs b/src/NSwag.CodeGeneration.CSharp.Tests/BinaryTests.cs
index 1f5a83cc33..195e8c12cd 100644
--- a/src/NSwag.CodeGeneration.CSharp.Tests/BinaryTests.cs
+++ b/src/NSwag.CodeGeneration.CSharp.Tests/BinaryTests.cs
@@ -442,7 +442,7 @@ public async Task When_multipart_with_ref_should_read_schema()
             var code = codeGenerator.GenerateFile();
 
             //// Assert
-            Assert.Contains("public virtual async System.Threading.Tasks.Task<CreateAddFileResponse> AddFileAsync(FileParameter file, Model? model, System.Threading.CancellationToken cancellationToken)", code);
+            Assert.Contains("public virtual async System.Threading.Tasks.Task<CreateAddFileResponse> AddFileAsync(FileParameter file, Model model, System.Threading.CancellationToken cancellationToken)", code);
             Assert.Contains("var content_file_ = new System.Net.Http.StreamContent(file.Data);", code);
             Assert.Contains("public partial class FileParameter", code);
         }
@@ -504,7 +504,7 @@ public async Task When_multipart_inline_schema()
             var code = codeGenerator.GenerateFile();
 
             //// Assert
-            Assert.Contains("public virtual async System.Threading.Tasks.Task<CreateAddFileResponse> AddFileAsync(FileParameter file, Model? model, System.Threading.CancellationToken cancellationToken)", code);
+            Assert.Contains("public virtual async System.Threading.Tasks.Task<CreateAddFileResponse> AddFileAsync(FileParameter file, Model model, System.Threading.CancellationToken cancellationToken)", code);
             Assert.Contains("var content_file_ = new System.Net.Http.StreamContent(file.Data);", code);
             Assert.Contains("public partial class FileParameter", code);
         }
diff --git a/src/NSwag.CodeGeneration.CSharp/Templates/Client.Class.liquid b/src/NSwag.CodeGeneration.CSharp/Templates/Client.Class.liquid
index 52400fa632..6862d9c26c 100644
--- a/src/NSwag.CodeGeneration.CSharp/Templates/Client.Class.liquid
+++ b/src/NSwag.CodeGeneration.CSharp/Templates/Client.Class.liquid
@@ -247,7 +247,7 @@
                 content_.Headers.Remove("Content-Type");
                 content_.Headers.TryAddWithoutValidation("Content-Type", "multipart/form-data; boundary=" + boundary_);
 {%                 for parameter in operation.FormParameters %}
-{%                     if parameter.IsNullable -%}
+{%                     if parameter.IsNullable or parameter.IsOptional -%}
                 if ({{ parameter.VariableName }} != null)
 {%                     else -%}
                 if ({{ parameter.VariableName }} == null)
diff --git a/src/NSwag.CodeGeneration/Models/OperationModelBase.cs b/src/NSwag.CodeGeneration/Models/OperationModelBase.cs
index 9af99efa68..7fcb09a375 100644
--- a/src/NSwag.CodeGeneration/Models/OperationModelBase.cs
+++ b/src/NSwag.CodeGeneration/Models/OperationModelBase.cs
@@ -366,7 +366,8 @@ protected IList<OpenApiParameter> GetActualParameters()
                         OpenApiParameterCollectionFormat.Multi : OpenApiParameterCollectionFormat.Undefined,
                     //Explode = p.Value.Type.HasFlag(JsonObjectType.Array) && p.Value.Item != null,
                     //Schema = p.Value.Type.HasFlag(JsonObjectType.Array) && p.Value.Item != null ? p.Value.Item : p.Value,
-                    Position = parameters.Count + 100 + i
+                    Position = parameters.Count + 100 + i,
+                    IsRequired = p.Value.IsRequired
                 })).ToList();
             }