diff --git a/crates/imap/src/op/authenticate.rs b/crates/imap/src/op/authenticate.rs
index d85d5d57e..5846bb445 100644
--- a/crates/imap/src/op/authenticate.rs
+++ b/crates/imap/src/op/authenticate.rs
@@ -233,14 +233,10 @@ pub fn decode_challenge_plain(challenge: &[u8]) -> Result<Credentials<String>, &
     let mut arg_num = 0;
     for &ch in challenge {
         if ch != 0 {
-            match arg_num.cmp(&2) {
-                std::cmp::Ordering::Less => {
-                    username.push(ch);
-                }
-                std::cmp::Ordering::Equal => {
-                    secret.push(ch);
-                }
-                std::cmp::Ordering::Greater => (),
+            if arg_num == 1 {
+                username.push(ch);
+            } else if arg_num == 2 {
+                secret.push(ch);
             }
         } else {
             arg_num += 1;