diff --git a/lib/common_test/src/ct_telnet.erl b/lib/common_test/src/ct_telnet.erl
index 089e13683282..de3cd0b9ae44 100644
--- a/lib/common_test/src/ct_telnet.erl
+++ b/lib/common_test/src/ct_telnet.erl
@@ -187,8 +187,7 @@ Regular expression matching all possible prompts for a specific target type.
 STDLIB) must return a list with one single element.
 """.
 -type prompt_regexp() :: string().
--type ascii_char() :: 0..127.
--type send_option() :: {'newline', boolean() | [ascii_char()]}.
+-type send_option() :: {'newline', boolean() | string()}.
 -export_type([connection/0, connection_type/0, handle/0, prompt_regexp/0]).
 
 -record(state,{host,