diff --git a/core/src/types/user.rs b/core/src/types/user.rs
index a9baa5b..d014453 100644
--- a/core/src/types/user.rs
+++ b/core/src/types/user.rs
@@ -114,7 +114,7 @@ impl NicknameStr {
 }
 
 #[str(fixed(error = ParseError))]
-pub struct SignUpCompletionToken(Seq<16, ascii::Printable>);
+pub struct SignUpCompletionToken(Seq<16, ascii::UrlSafe>);
 
 // TODO: impl this from macro.
 impl rand::distr::Distribution<SignUpCompletionToken> for rand::distr::StandardUniform {