diff --git a/src/RestSharp/Parameters/HeaderParameter.cs b/src/RestSharp/Parameters/HeaderParameter.cs
index 7dce5df92..76fc0b75a 100644
--- a/src/RestSharp/Parameters/HeaderParameter.cs
+++ b/src/RestSharp/Parameters/HeaderParameter.cs
@@ -53,7 +53,6 @@ static bool IsInvalidHeaderString(string stringValue) {
         // ReSharper disable once ForCanBeConvertedToForeach
         for (var i = 0; i < stringValue.Length; i++) {
             switch (stringValue[i]) {
-                case '\t':
                 case '\r':
                 case '\n':
                     return true;