diff --git a/Cargo.toml b/Cargo.toml
index 9a60da04..f55a82e5 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -45,6 +45,7 @@ items_after_statements = "warn"
 let_underscore_must_use = "warn"
 lossy_float_literal = "warn"
 manual_let_else = "warn"
+manual_string_new = "warn"
 mem_forget = "warn"
 missing_assert_message = "warn"
 mod_module_files = "warn"
diff --git a/src/api/client_server/room.rs b/src/api/client_server/room.rs
index 420e7110..ad43b957 100644
--- a/src/api/client_server/room.rs
+++ b/src/api/client_server/room.rs
@@ -228,7 +228,7 @@ pub(crate) async fn create_room_route(
                 event_type: TimelineEventType::RoomCreate,
                 content: to_raw_value(&content).expect("event is valid, we just created it"),
                 unsigned: None,
-                state_key: Some("".to_owned()),
+                state_key: Some(String::new()),
                 redacts: None,
             },
             sender_user,
@@ -309,7 +309,7 @@ pub(crate) async fn create_room_route(
                 content: to_raw_value(&power_levels_content)
                     .expect("to_raw_value always works on serde_json::Value"),
                 unsigned: None,
-                state_key: Some("".to_owned()),
+                state_key: Some(String::new()),
                 redacts: None,
             },
             sender_user,
@@ -332,7 +332,7 @@ pub(crate) async fn create_room_route(
                     })
                     .expect("We checked that alias earlier, it must be fine"),
                     unsigned: None,
-                    state_key: Some("".to_owned()),
+                    state_key: Some(String::new()),
                     redacts: None,
                 },
                 sender_user,
@@ -358,7 +358,7 @@ pub(crate) async fn create_room_route(
                 }))
                 .expect("event is valid, we just created it"),
                 unsigned: None,
-                state_key: Some("".to_owned()),
+                state_key: Some(String::new()),
                 redacts: None,
             },
             sender_user,
@@ -379,7 +379,7 @@ pub(crate) async fn create_room_route(
                 ))
                 .expect("event is valid, we just created it"),
                 unsigned: None,
-                state_key: Some("".to_owned()),
+                state_key: Some(String::new()),
                 redacts: None,
             },
             sender_user,
@@ -401,7 +401,7 @@ pub(crate) async fn create_room_route(
                 }))
                 .expect("event is valid, we just created it"),
                 unsigned: None,
-                state_key: Some("".to_owned()),
+                state_key: Some(String::new()),
                 redacts: None,
             },
             sender_user,
@@ -418,7 +418,7 @@ pub(crate) async fn create_room_route(
         })?;
 
         // Implicit state key defaults to ""
-        pdu_builder.state_key.get_or_insert_with(|| "".to_owned());
+        pdu_builder.state_key.get_or_insert_with(String::new);
 
         // Silently skip encryption events if they are not allowed
         if pdu_builder.event_type == TimelineEventType::RoomEncryption
@@ -445,7 +445,7 @@ pub(crate) async fn create_room_route(
                     content: to_raw_value(&RoomNameEventContent::new(name.clone()))
                         .expect("event is valid, we just created it"),
                     unsigned: None,
-                    state_key: Some("".to_owned()),
+                    state_key: Some(String::new()),
                     redacts: None,
                 },
                 sender_user,
@@ -467,7 +467,7 @@ pub(crate) async fn create_room_route(
                     })
                     .expect("event is valid, we just created it"),
                     unsigned: None,
-                    state_key: Some("".to_owned()),
+                    state_key: Some(String::new()),
                     redacts: None,
                 },
                 sender_user,
@@ -628,7 +628,7 @@ pub(crate) async fn upgrade_room_route(
                 })
                 .expect("event is valid, we just created it"),
                 unsigned: None,
-                state_key: Some("".to_owned()),
+                state_key: Some(String::new()),
                 redacts: None,
             },
             sender_user,
@@ -729,7 +729,7 @@ pub(crate) async fn upgrade_room_route(
                 content: to_raw_value(&create_event_content)
                     .expect("event is valid, we just created it"),
                 unsigned: None,
-                state_key: Some("".to_owned()),
+                state_key: Some(String::new()),
                 redacts: None,
             },
             sender_user,
@@ -799,7 +799,7 @@ pub(crate) async fn upgrade_room_route(
                     event_type: event_type.to_string().into(),
                     content: event_content,
                     unsigned: None,
-                    state_key: Some("".to_owned()),
+                    state_key: Some(String::new()),
                     redacts: None,
                 },
                 sender_user,
@@ -849,7 +849,7 @@ pub(crate) async fn upgrade_room_route(
                 content: to_raw_value(&power_levels_event_content)
                     .expect("event is valid, we just created it"),
                 unsigned: None,
-                state_key: Some("".to_owned()),
+                state_key: Some(String::new()),
                 redacts: None,
             },
             sender_user,
diff --git a/src/service/admin.rs b/src/service/admin.rs
index 58ef401a..2da95e13 100644
--- a/src/service/admin.rs
+++ b/src/service/admin.rs
@@ -983,7 +983,7 @@ impl Service {
                     event_type: TimelineEventType::RoomCreate,
                     content: to_raw_value(&content).expect("event is valid, we just created it"),
                     unsigned: None,
-                    state_key: Some("".to_owned()),
+                    state_key: Some(String::new()),
                     redacts: None,
                 },
                 &grapevine_user,
@@ -1036,7 +1036,7 @@ impl Service {
                     })
                     .expect("event is valid, we just created it"),
                     unsigned: None,
-                    state_key: Some("".to_owned()),
+                    state_key: Some(String::new()),
                     redacts: None,
                 },
                 &grapevine_user,
@@ -1055,7 +1055,7 @@ impl Service {
                     content: to_raw_value(&RoomJoinRulesEventContent::new(JoinRule::Invite))
                         .expect("event is valid, we just created it"),
                     unsigned: None,
-                    state_key: Some("".to_owned()),
+                    state_key: Some(String::new()),
                     redacts: None,
                 },
                 &grapevine_user,
@@ -1076,7 +1076,7 @@ impl Service {
                     ))
                     .expect("event is valid, we just created it"),
                     unsigned: None,
-                    state_key: Some("".to_owned()),
+                    state_key: Some(String::new()),
                     redacts: None,
                 },
                 &grapevine_user,
@@ -1097,7 +1097,7 @@ impl Service {
                     ))
                     .expect("event is valid, we just created it"),
                     unsigned: None,
-                    state_key: Some("".to_owned()),
+                    state_key: Some(String::new()),
                     redacts: None,
                 },
                 &grapevine_user,
@@ -1117,7 +1117,7 @@ impl Service {
                     content: to_raw_value(&RoomNameEventContent::new(room_name))
                         .expect("event is valid, we just created it"),
                     unsigned: None,
-                    state_key: Some("".to_owned()),
+                    state_key: Some(String::new()),
                     redacts: None,
                 },
                 &grapevine_user,
@@ -1137,7 +1137,7 @@ impl Service {
                     })
                     .expect("event is valid, we just created it"),
                     unsigned: None,
-                    state_key: Some("".to_owned()),
+                    state_key: Some(String::new()),
                     redacts: None,
                 },
                 &grapevine_user,
@@ -1163,7 +1163,7 @@ impl Service {
                     })
                     .expect("event is valid, we just created it"),
                     unsigned: None,
-                    state_key: Some("".to_owned()),
+                    state_key: Some(String::new()),
                     redacts: None,
                 },
                 &grapevine_user,
@@ -1288,7 +1288,7 @@ impl Service {
                         })
                         .expect("event is valid, we just created it"),
                         unsigned: None,
-                        state_key: Some("".to_owned()),
+                        state_key: Some(String::new()),
                         redacts: None,
                     },
                     &grapevine_user,
diff --git a/src/service/rooms/event_handler.rs b/src/service/rooms/event_handler.rs
index 5587a303..22edf677 100644
--- a/src/service/rooms/event_handler.rs
+++ b/src/service/rooms/event_handler.rs
@@ -435,7 +435,7 @@ impl Service {
             // The original create event must be in the auth events
             if !matches!(
                 auth_events
-                    .get(&(StateEventType::RoomCreate, "".to_owned()))
+                    .get(&(StateEventType::RoomCreate, String::new()))
                     .map(|a| a.as_ref()),
                 Some(_) | None
             ) {