diff --git a/proto/control-api/src/control/member.rs b/proto/control-api/src/control/member.rs
index 272bbbb4..986cd881 100644
--- a/proto/control-api/src/control/member.rs
+++ b/proto/control-api/src/control/member.rs
@@ -3,7 +3,7 @@
 use std::{
     cmp::Ordering,
     collections::HashMap,
-    fmt,
+    fmt::Write as _,
     hash::{Hash, Hasher},
     time::Duration,
 };
@@ -152,13 +152,21 @@ pub struct Sid {
     pub creds: Option<PlainCredentials>,
 }
 
-impl Display for Sid {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        write!(f, "{}/{}/{}", self.public_url, self.room_id, self.member_id)?;
+impl Sid {
+    /// Exposes [Sid] to connect to a media server with a credentials.
+    pub fn expose(&self) -> String {
+        let mut sid = String::new();
+        write!(
+            sid,
+            "{}/{}/{}",
+            self.public_url, self.room_id, self.member_id
+        )
+        .expect("write to `String` never fails");
         if let Some(plain) = &self.creds {
-            write!(f, "?token={}", plain.expose_str())?;
+            write!(sid, "?token={}", plain.expose_str())
+                .expect("write to `String` never fails");
         }
-        Ok(())
+        sid
     }
 }
 
diff --git a/proto/control-api/src/grpc/server.rs b/proto/control-api/src/grpc/server.rs
index dcf2b84f..131516a4 100644
--- a/proto/control-api/src/grpc/server.rs
+++ b/proto/control-api/src/grpc/server.rs
@@ -45,7 +45,7 @@ where
             Ok(sids) => control_proto::CreateResponse {
                 sid: sids
                     .into_iter()
-                    .map(|(id, sid)| (id.to_string(), sid.to_string()))
+                    .map(|(id, sid)| (id.to_string(), sid.expose()))
                     .collect(),
                 error: None,
             },
@@ -129,7 +129,7 @@ where
             Ok(sids) => control_proto::CreateResponse {
                 sid: sids
                     .into_iter()
-                    .map(|(id, sid)| (id.to_string(), sid.to_string()))
+                    .map(|(id, sid)| (id.to_string(), sid.expose()))
                     .collect(),
                 error: None,
             },