diff --git a/modules/swagger-codegen/src/main/resources/csharp/modelGeneric.mustache b/modules/swagger-codegen/src/main/resources/csharp/modelGeneric.mustache
index e8a543b2a0..255984ded5 100644
--- a/modules/swagger-codegen/src/main/resources/csharp/modelGeneric.mustache
+++ b/modules/swagger-codegen/src/main/resources/csharp/modelGeneric.mustache
@@ -241,13 +241,15 @@ this.{{name}} = {{name}};
 
             {{/minimum}}
             {{#pattern}}
+            {{^isByteArray}}
             // {{{name}}} ({{{datatype}}}) pattern
             Regex regex{{{name}}} = new Regex(@"{{{vendorExtensions.x-regex}}}"{{#vendorExtensions.x-modifiers}}{{#-first}}, {{/-first}}RegexOptions.{{{.}}}{{^-last}} | {{/-last}}{{/vendorExtensions.x-modifiers}});
             if (false == regex{{{name}}}.Match(this.{{{name}}}).Success)
             {
-                yield return new System.ComponentModel.DataAnnotations.ValidationResult("Invalid value for {{{name}}}, must match a pattern of {{{pattern}}}.", new [] { "{{{name}}}" });
+                yield return new System.ComponentModel.DataAnnotations.ValidationResult("Invalid value for {{{name}}}, must match a pattern of " + regex{{{name}}}, new [] { "{{{name}}}" });
             }
 
+            {{/isByteArray}}
             {{/pattern}}
             {{/hasValidation}}
             {{/vars}}
diff --git a/samples/client/petstore/csharp/SwaggerClient/src/IO.Swagger/Model/FormatTest.cs b/samples/client/petstore/csharp/SwaggerClient/src/IO.Swagger/Model/FormatTest.cs
index 2bf7d5997d..ddf16ddad5 100644
--- a/samples/client/petstore/csharp/SwaggerClient/src/IO.Swagger/Model/FormatTest.cs
+++ b/samples/client/petstore/csharp/SwaggerClient/src/IO.Swagger/Model/FormatTest.cs
@@ -415,7 +415,7 @@ namespace IO.Swagger.Model
             Regex regex_String = new Regex(@"[a-z]", RegexOptions.CultureInvariant | RegexOptions.IgnoreCase);
             if (false == regex_String.Match(this._String).Success)
             {
-                yield return new System.ComponentModel.DataAnnotations.ValidationResult("Invalid value for _String, must match a pattern of /[a-z]/i.", new [] { "_String" });
+                yield return new System.ComponentModel.DataAnnotations.ValidationResult("Invalid value for _String, must match a pattern of " + regex_String, new [] { "_String" });
             }
 
             // _Byte (byte[]) pattern
diff --git a/samples/client/petstore/csharp/SwaggerClientWithPropertyChanged/src/IO.Swagger/Model/FormatTest.cs b/samples/client/petstore/csharp/SwaggerClientWithPropertyChanged/src/IO.Swagger/Model/FormatTest.cs
index 8762cbe975..706354c7b2 100644
--- a/samples/client/petstore/csharp/SwaggerClientWithPropertyChanged/src/IO.Swagger/Model/FormatTest.cs
+++ b/samples/client/petstore/csharp/SwaggerClientWithPropertyChanged/src/IO.Swagger/Model/FormatTest.cs
@@ -438,7 +438,7 @@ namespace IO.Swagger.Model
             Regex regex_String = new Regex(@"[a-z]", RegexOptions.CultureInvariant | RegexOptions.IgnoreCase);
             if (false == regex_String.Match(this._String).Success)
             {
-                yield return new System.ComponentModel.DataAnnotations.ValidationResult("Invalid value for _String, must match a pattern of /[a-z]/i.", new [] { "_String" });
+                yield return new System.ComponentModel.DataAnnotations.ValidationResult("Invalid value for _String, must match a pattern of " + regex_String, new [] { "_String" });
             }
 
             // _Byte (byte[]) pattern