diff --git a/backend-rs/src/auth.rs b/backend-rs/src/auth.rs
index 924c731..fe12789 100644
--- a/backend-rs/src/auth.rs
+++ b/backend-rs/src/auth.rs
@@ -20,6 +20,8 @@ use crate::state::AppState;
 pub struct Claims {
     pub user_id: i32,
     pub token_type: String,
+    // Read by jsonwebtoken's `validate_exp` during decode, not by our code.
+    #[allow(dead_code)]
     pub exp: usize,
 }
 
diff --git a/backend-rs/src/routes/admin.rs b/backend-rs/src/routes/admin.rs
index 41f9c5e..f77c91f 100644
--- a/backend-rs/src/routes/admin.rs
+++ b/backend-rs/src/routes/admin.rs
@@ -341,7 +341,7 @@ async fn send_test_email(
         &state.config.email,
         "Holy Flavors Admin Test Email",
         &body,
-        &[me.email.clone()],
+        std::slice::from_ref(&me.email),
     )
     .await
     {
diff --git a/backend-rs/src/routes/users.rs b/backend-rs/src/routes/users.rs
index c9f2421..4e2d7f7 100644
--- a/backend-rs/src/routes/users.rs
+++ b/backend-rs/src/routes/users.rs
@@ -733,7 +733,7 @@ async fn signup(
         &state.config.email,
         "Verify your Holy Flavors account",
         &msg,
-        &[email.clone()],
+        std::slice::from_ref(&email),
     )
     .await
     {