diff --git a/.cargo/config.toml b/.cargo/config.toml
index 5a58ebb3..857af392 100644
--- a/.cargo/config.toml
+++ b/.cargo/config.toml
@@ -17,6 +17,7 @@ ruma-clippy = """\
     -W clippy::mut_mut \
     -W clippy::needless_borrow \
     -A clippy::new_without_default \
+    -W clippy::str_to_string \
     -W clippy::todo \
     -W clippy::unreadable_literal \
     -W clippy::unseparated_literal_suffix \
diff --git a/crates/ruma-api-macros/src/api/request/outgoing.rs b/crates/ruma-api-macros/src/api/request/outgoing.rs
index cfaee60e..b7e587a2 100644
--- a/crates/ruma-api-macros/src/api/request/outgoing.rs
+++ b/crates/ruma-api-macros/src/api/request/outgoing.rs
@@ -38,7 +38,7 @@ impl Request {
                 );
                 format_args.push(quote! {
                     #percent_encoding::utf8_percent_encode(
-                        &self.#path_var.to_string(),
+                        &::std::string::ToString::to_string(&self.#path_var),
                         #percent_encoding::NON_ALPHANUMERIC,
                     )
                 });
diff --git a/crates/ruma-events/src/key/verification/start.rs b/crates/ruma-events/src/key/verification/start.rs
index 6b116afa..4eb47dc7 100644
--- a/crates/ruma-events/src/key/verification/start.rs
+++ b/crates/ruma-events/src/key/verification/start.rs
@@ -394,7 +394,7 @@ mod tests {
 
         #[cfg(feature = "unstable-pre-spec")]
         {
-            let secret = "This is a secret to everybody".to_string();
+            let secret = "This is a secret to everybody".to_owned();
 
             let key_verification_start_content = StartToDeviceEventContent {
                 from_device: "123".into(),
@@ -447,7 +447,7 @@ mod tests {
 
         assert_eq!(to_json_value(&key_verification_start_content).unwrap(), json_data);
 
-        let secret = "This is a secret to everybody".to_string();
+        let secret = "This is a secret to everybody".to_owned();
 
         let key_verification_start_content = StartEventContent {
             from_device: "123".into(),
diff --git a/crates/ruma-signatures/src/keys.rs b/crates/ruma-signatures/src/keys.rs
index 8dbe14da..8a6ce692 100644
--- a/crates/ruma-signatures/src/keys.rs
+++ b/crates/ruma-signatures/src/keys.rs
@@ -213,7 +213,7 @@ mod tests {
 
     #[test]
     fn ring_key() {
-        let keypair = Ed25519KeyPair::from_der(RING_DOC, "".to_string()).unwrap();
+        let keypair = Ed25519KeyPair::from_der(RING_DOC, "".to_owned()).unwrap();
 
         assert_eq!(keypair.pubkey.as_bytes(), RING_PUBKEY);
     }
diff --git a/crates/ruma-state-res/benches/state_res_bench.rs b/crates/ruma-state-res/benches/state_res_bench.rs
index d56e6a15..6deb169d 100644
--- a/crates/ruma-state-res/benches/state_res_bench.rs
+++ b/crates/ruma-state-res/benches/state_res_bench.rs
@@ -354,11 +354,11 @@ where
     // We don't care if the addition happens in order just that it is atomic
     // (each event has its own value)
     let ts = SERVER_TIMESTAMP.fetch_add(1, SeqCst);
-    let id = if id.contains('$') { id.to_string() } else { format!("${}:foo", id) };
+    let id = if id.contains('$') { id.to_owned() } else { format!("${}:foo", id) };
     let auth_events = auth_events.iter().map(AsRef::as_ref).map(event_id).collect::<Vec<_>>();
     let prev_events = prev_events.iter().map(AsRef::as_ref).map(event_id).collect::<Vec<_>>();
 
-    let state_key = state_key.map(ToString::to_string);
+    let state_key = state_key.map(ToOwned::to_owned);
     Arc::new(StateEvent {
         event_id: EventId::try_from(id).unwrap(),
         rest: Pdu::RoomV3Pdu(RoomV3Pdu {
diff --git a/crates/ruma-state-res/src/event_auth.rs b/crates/ruma-state-res/src/event_auth.rs
index a6a549f7..c000c8ec 100644
--- a/crates/ruma-state-res/src/event_auth.rs
+++ b/crates/ruma-state-res/src/event_auth.rs
@@ -30,9 +30,9 @@ pub fn auth_types_for_event(
     }
 
     let mut auth_types = vec![
-        (EventType::RoomPowerLevels, "".to_string()),
+        (EventType::RoomPowerLevels, "".to_owned()),
         (EventType::RoomMember, sender.to_string()),
-        (EventType::RoomCreate, "".to_string()),
+        (EventType::RoomCreate, "".to_owned()),
     ];
 
     if kind == &EventType::RoomMember {
@@ -42,7 +42,7 @@ pub fn auth_types_for_event(
                 .map(|m| serde_json::from_value::<MembershipState>(m.clone()))
             {
                 if [MembershipState::Join, MembershipState::Invite].contains(&membership) {
-                    let key = (EventType::RoomJoinRules, "".to_string());
+                    let key = (EventType::RoomJoinRules, "".to_owned());
                     if !auth_types.contains(&key) {
                         auth_types.push(key)
                     }
@@ -165,7 +165,7 @@ pub fn auth_check<E: Event>(
     */
 
     // 3. If event does not have m.room.create in auth_events reject
-    if auth_events.get(&(EventType::RoomCreate, "".to_string())).is_none() {
+    if auth_events.get(&(EventType::RoomCreate, "".to_owned())).is_none() {
         warn!("no m.room.create event in auth chain");
 
         return Ok(false);
diff --git a/crates/ruma-state-res/tests/event_sorting.rs b/crates/ruma-state-res/tests/event_sorting.rs
index be5570ee..2c9fcab4 100644
--- a/crates/ruma-state-res/tests/event_sorting.rs
+++ b/crates/ruma-state-res/tests/event_sorting.rs
@@ -49,7 +49,7 @@ fn test_event_sort() {
 
     events_to_sort.shuffle(&mut rand::thread_rng());
 
-    let power_level = resolved_power.get(&(EventType::RoomPowerLevels, "".to_string()));
+    let power_level = resolved_power.get(&(EventType::RoomPowerLevels, "".to_owned()));
 
     let sorted_event_ids =
         StateResolution::mainline_sort(&room_id(), &events_to_sort, power_level, &mut events);
diff --git a/crates/ruma-state-res/tests/utils.rs b/crates/ruma-state-res/tests/utils.rs
index b78ba006..774824a8 100644
--- a/crates/ruma-state-res/tests/utils.rs
+++ b/crates/ruma-state-res/tests/utils.rs
@@ -198,7 +198,7 @@ pub fn do_check(
                 // Filter out the dummy messages events.
                 // These act as points in time where there should be a known state to
                 // test against.
-                && **k != (EventType::RoomMessage, "dummy".to_string())
+                && **k != (EventType::RoomMessage, "dummy".to_owned())
         })
         .map(|(k, v)| (k.clone(), v.clone()))
         .collect::<StateMap<EventId>>();
@@ -317,9 +317,9 @@ pub fn to_init_pdu_event(
     content: JsonValue,
 ) -> Arc<StateEvent> {
     let ts = SERVER_TIMESTAMP.fetch_add(1, SeqCst);
-    let id = if id.contains('$') { id.to_string() } else { format!("${}:foo", id) };
+    let id = if id.contains('$') { id.to_owned() } else { format!("${}:foo", id) };
 
-    let state_key = state_key.map(ToString::to_string);
+    let state_key = state_key.map(ToOwned::to_owned);
     Arc::new(StateEvent {
         event_id: EventId::try_from(id).unwrap(),
         rest: Pdu::RoomV3Pdu(RoomV3Pdu {
@@ -355,11 +355,11 @@ where
     S: AsRef<str>,
 {
     let ts = SERVER_TIMESTAMP.fetch_add(1, SeqCst);
-    let id = if id.contains('$') { id.to_string() } else { format!("${}:foo", id) };
+    let id = if id.contains('$') { id.to_owned() } else { format!("${}:foo", id) };
     let auth_events = auth_events.iter().map(AsRef::as_ref).map(event_id).collect::<Vec<_>>();
     let prev_events = prev_events.iter().map(AsRef::as_ref).map(event_id).collect::<Vec<_>>();
 
-    let state_key = state_key.map(ToString::to_string);
+    let state_key = state_key.map(ToOwned::to_owned);
     Arc::new(StateEvent {
         event_id: EventId::try_from(id).unwrap(),
         rest: Pdu::RoomV3Pdu(RoomV3Pdu {