diff --git a/endpoints/filter.go b/endpoints/filter.go
index 6386cb3..a29316b 100644
--- a/endpoints/filter.go
+++ b/endpoints/filter.go
@@ -47,7 +47,7 @@ func ValidateLengthAndCharset(value string, maxLength int, alphabet string) (str
 }
 
 func ValidateProtocolParam(value string) (string, error) {
-	return ValidateLengthAndCharset(value, 80, "ID_AS:.abcdef1234567890")
+	return ValidateLengthAndCharset(value, 80, "ABCDEFGHIJKLMNOPQRSTUVWXYZ_:.abcdefghijklmnopqrstuvwxyz1234567890")
 }
 
 func ValidatePrefixParam(value string) (string, error) {