diff --git a/http_code.go b/http_code.go
index 246d3cf..1199ea3 100644
--- a/http_code.go
+++ b/http_code.go
@@ -21,7 +21,11 @@ type HttpCode struct {
 func newHttpCodeData(httpCode int) HttpCode {
 	desc := http.StatusText(httpCode)
 	if len(desc) == 0 {
-		desc = fmt.Sprintf("%v: unknown error", httpCode)
+		if httpCode == 499 {
+			desc = "client request timeout"
+		} else {
+			desc = fmt.Sprintf("%v: unknown error", httpCode)
+		}
 	}
 	return HttpCode{
 		Value: httpCode,
@@ -90,6 +94,7 @@ var (
 		newHttpCodeData(http.StatusTooManyRequests),
 		newHttpCodeData(http.StatusRequestHeaderFieldsTooLarge),
 		newHttpCodeData(http.StatusUnavailableForLegalReasons),
+		newHttpCodeData(499),
 
 		// 5xx
 		newHttpCodeData(http.StatusInternalServerError),