diff --git a/ruma-events-macros/src/gen.rs b/ruma-events-macros/src/gen.rs
index 8dc09837..d6a67c32 100644
--- a/ruma-events-macros/src/gen.rs
+++ b/ruma-events-macros/src/gen.rs
@@ -153,7 +153,7 @@ impl ToTokens for RumaEvent {
                         }
 
                         /// Additional key-value pairs not signed by the homeserver.
-                        fn unsigned(&self) -> &serde_json::Map<String, serde_json::Value> {
+                        fn unsigned(&self) -> &std::collections::BTreeMap<String, serde_json::Value> {
                             &self.unsigned
                         }
                     }
@@ -295,8 +295,8 @@ fn populate_room_event_fields(content_name: Ident, fields: Vec<Field>) -> Vec<Fi
         pub sender: ruma_identifiers::UserId,
 
         /// Additional key-value pairs not signed by the homeserver.
-        #[serde(default, skip_serializing_if = "serde_json::Map::is_empty")]
-        pub unsigned: serde_json::Map<String, serde_json::Value>,
+        #[serde(default, skip_serializing_if = "std::collections::BTreeMap::is_empty")]
+        pub unsigned: std::collections::BTreeMap<String, serde_json::Value>,
     };
 
     fields.extend(punctuated_fields.into_iter().map(|p| p.field));
diff --git a/ruma-events-macros/src/lib.rs b/ruma-events-macros/src/lib.rs
index 793271b0..19159a1b 100644
--- a/ruma-events-macros/src/lib.rs
+++ b/ruma-events-macros/src/lib.rs
@@ -112,7 +112,7 @@ mod parse;
 ///             ///
 ///             /// A mapping of `UserId`'s to a collection of `RoomId`'s which are considered
 ///             /// *direct* for that particular user.
-///             std::collections::HashMap<ruma_identifiers::UserId, Vec<ruma_identifiers::RoomId>>
+///             std::collections::BTreeMap<ruma_identifiers::UserId, Vec<ruma_identifiers::RoomId>>
 ///         }
 ///     }
 /// }
diff --git a/src/direct.rs b/src/direct.rs
index 1d811fb0..c1b7392e 100644
--- a/src/direct.rs
+++ b/src/direct.rs
@@ -1,6 +1,6 @@
 //! Types for the *m.direct* event.
 
-use std::collections::HashMap;
+use std::collections::BTreeMap;
 
 use ruma_events_macros::ruma_event;
 use ruma_identifiers::{RoomId, UserId};
@@ -15,14 +15,14 @@ ruma_event! {
             ///
             /// A mapping of `UserId`s to a list of `RoomId`s which are considered *direct* for that
             /// particular user.
-            HashMap<UserId, Vec<RoomId>>
+            BTreeMap<UserId, Vec<RoomId>>
         },
     }
 }
 
 #[cfg(test)]
 mod tests {
-    use std::collections::HashMap;
+    use std::collections::BTreeMap;
 
     use ruma_identifiers::{RoomId, UserId};
     use serde_json::{from_value as from_json_value, json, to_value as to_json_value};
@@ -32,7 +32,7 @@ mod tests {
 
     #[test]
     fn serialization() {
-        let mut content: DirectEventContent = HashMap::new();
+        let mut content: DirectEventContent = BTreeMap::new();
         let alice = UserId::new("ruma.io").unwrap();
         let room = vec![RoomId::new("ruma.io").unwrap()];
 
diff --git a/src/event_type.rs b/src/event_type.rs
index ee37d978..199bda1a 100644
--- a/src/event_type.rs
+++ b/src/event_type.rs
@@ -6,7 +6,7 @@ use std::{
 use serde::{Deserialize, Serialize};
 
 /// The type of an event.
-#[derive(Clone, Debug, Eq, Hash, PartialEq, Serialize, Deserialize)]
+#[derive(Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Serialize, Deserialize)]
 // Cow<str> because deserialization sometimes needs to copy to unescape things
 #[serde(from = "Cow<'_, str>", into = "String")]
 pub enum EventType {
diff --git a/src/from_raw.rs b/src/from_raw.rs
index 95213391..07d27b88 100644
--- a/src/from_raw.rs
+++ b/src/from_raw.rs
@@ -1,4 +1,4 @@
-use std::{collections::HashMap, convert::Infallible, fmt::Display};
+use std::{collections::BTreeMap, convert::Infallible, fmt::Display};
 
 use serde::de::DeserializeOwned;
 
@@ -35,7 +35,7 @@ impl FromRaw for serde_json::Value {
     }
 }
 
-impl<K, V, S> FromRaw for HashMap<K, V, S>
+impl<K, V> FromRaw for BTreeMap<K, V>
 where
     Self: DeserializeOwned,
 {
diff --git a/src/key/verification/mac.rs b/src/key/verification/mac.rs
index 1aad1d9a..488d2d3f 100644
--- a/src/key/verification/mac.rs
+++ b/src/key/verification/mac.rs
@@ -1,6 +1,6 @@
 //! Types for the *m.key.verification.mac* event.
 
-use std::collections::HashMap;
+use std::collections::BTreeMap;
 
 use ruma_events_macros::ruma_event;
 
@@ -20,7 +20,7 @@ ruma_event! {
             /// A map of the key ID to the MAC of the key, using the algorithm in the verification process.
             ///
             /// The MAC is encoded as unpadded Base64.
-            pub mac: HashMap<String, String>,
+            pub mac: BTreeMap<String, String>,
 
             /// The MAC of the comma-separated, sorted, list of key IDs given in the `mac` property, encoded
             /// as unpadded Base64.
diff --git a/src/lib.rs b/src/lib.rs
index 7ada0346..04121df5 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -44,7 +44,7 @@
 //!     They have at least the following additional keys:
 //!     *   `state_key`, a string which serves as a sort of "sub-type."
 //!         The state key allows a room to persist multiple state events of the same type.
-//!         You can think of a room's state events as being a `HashMap` where the keys are the tuple
+//!         You can think of a room's state events as being a `BTreeMap` where the keys are the tuple
 //!         `(event_type, state_key)`.
 //!     *   Optionally, `prev_content`, a JSON object containing the `content` object from the
 //!     previous event of the given `(event_type, state_key)` tuple in the given room.
@@ -116,6 +116,7 @@
 #![allow(clippy::use_self)]
 
 use std::{
+    collections::BTreeMap,
     error::Error,
     fmt::{Debug, Display, Formatter, Result as FmtResult},
     time::SystemTime,
@@ -127,7 +128,7 @@ use serde::{
     ser::SerializeMap,
     Deserialize, Deserializer, Serialize, Serializer,
 };
-use serde_json::{Map, Value};
+use serde_json::Value;
 
 pub use self::{custom::CustomEvent, custom_room::CustomRoomEvent, custom_state::CustomStateEvent};
 
@@ -317,7 +318,7 @@ impl Error for FromStrError {}
 /// A meaningless value that serializes to an empty JSON object.
 ///
 /// This type is used in a few places where the Matrix specification requires an empty JSON object,
-/// but it's wasteful to represent it as a `HashMap` in Rust code.
+/// but it's wasteful to represent it as a `BTreeMap` in Rust code.
 #[derive(Clone, Debug, PartialEq)]
 pub struct Empty;
 
@@ -394,7 +395,7 @@ pub trait RoomEvent: Event {
     fn sender(&self) -> &UserId;
 
     /// Additional key-value pairs not signed by the homeserver.
-    fn unsigned(&self) -> &Map<String, Value>;
+    fn unsigned(&self) -> &BTreeMap<String, Value>;
 }
 
 /// An event that describes persistent state about a room.
@@ -459,13 +460,13 @@ mod custom {
 }
 
 mod custom_room {
-    use std::time::SystemTime;
+    use std::{collections::BTreeMap, time::SystemTime};
 
     use super::{Event, EventType, RoomEvent};
 
     use ruma_events_macros::FromRaw;
     use serde::{Deserialize, Serialize};
-    use serde_json::{Map, Value};
+    use serde_json::Value;
 
     /// A custom room event not covered by the Matrix specification.
     #[derive(Clone, Debug, FromRaw, PartialEq, Serialize)]
@@ -485,8 +486,8 @@ mod custom_room {
         /// The unique identifier for the user who sent this event.
         pub sender: ruma_identifiers::UserId,
         /// Additional key-value pairs not signed by the homeserver.
-        #[serde(skip_serializing_if = "serde_json::Map::is_empty")]
-        pub unsigned: Map<String, Value>,
+        #[serde(skip_serializing_if = "std::collections::BTreeMap::is_empty")]
+        pub unsigned: BTreeMap<String, Value>,
     }
 
     /// The payload for `CustomRoomEvent`.
@@ -532,7 +533,7 @@ mod custom_room {
         }
 
         /// Additional key-value pairs not signed by the homeserver.
-        fn unsigned(&self) -> &Map<String, Value> {
+        fn unsigned(&self) -> &BTreeMap<String, Value> {
             &self.unsigned
         }
     }
@@ -559,19 +560,19 @@ mod custom_room {
             pub sender: ruma_identifiers::UserId,
             /// Additional key-value pairs not signed by the homeserver.
             #[serde(default)]
-            pub unsigned: Map<String, Value>,
+            pub unsigned: BTreeMap<String, Value>,
         }
     }
 }
 
 mod custom_state {
-    use std::time::SystemTime;
+    use std::{collections::BTreeMap, time::SystemTime};
 
     use super::{Event, EventType, RoomEvent, StateEvent};
 
     use ruma_events_macros::FromRaw;
     use serde::{Deserialize, Serialize};
-    use serde_json::{Map, Value};
+    use serde_json::Value;
 
     /// A custom state event not covered by the Matrix specification.
     #[derive(Clone, Debug, FromRaw, PartialEq, Serialize)]
@@ -595,8 +596,8 @@ mod custom_state {
         /// A key that determines which piece of room state the event represents.
         pub state_key: String,
         /// Additional key-value pairs not signed by the homeserver.
-        #[serde(skip_serializing_if = "serde_json::Map::is_empty")]
-        pub unsigned: Map<String, Value>,
+        #[serde(skip_serializing_if = "std::collections::BTreeMap::is_empty")]
+        pub unsigned: BTreeMap<String, Value>,
     }
 
     /// The payload for `CustomStateEvent`.
@@ -642,7 +643,7 @@ mod custom_state {
         }
 
         /// Additional key-value pairs not signed by the homeserver.
-        fn unsigned(&self) -> &Map<String, Value> {
+        fn unsigned(&self) -> &BTreeMap<String, Value> {
             &self.unsigned
         }
     }
@@ -685,7 +686,7 @@ mod custom_state {
             pub state_key: String,
             /// Additional key-value pairs not signed by the homeserver.
             #[serde(default)]
-            pub unsigned: Map<String, Value>,
+            pub unsigned: BTreeMap<String, Value>,
         }
     }
 }
diff --git a/src/macros.rs b/src/macros.rs
index fede51ea..2590f7a8 100644
--- a/src/macros.rs
+++ b/src/macros.rs
@@ -72,7 +72,7 @@ macro_rules! impl_room_event {
             }
 
             /// Additional key-value pairs not signed by the homeserver.
-            fn unsigned(&self) -> &::serde_json::Map<String, ::serde_json::Value> {
+            fn unsigned(&self) -> &::std::collections::BTreeMap<String, ::serde_json::Value> {
                 &self.unsigned
             }
         }
diff --git a/src/receipt.rs b/src/receipt.rs
index 8c63ed22..b0492995 100644
--- a/src/receipt.rs
+++ b/src/receipt.rs
@@ -1,6 +1,6 @@
 //! Types for the *m.receipt* event.
 
-use std::{collections::HashMap, time::SystemTime};
+use std::{collections::BTreeMap, time::SystemTime};
 
 use ruma_events_macros::ruma_event;
 use ruma_identifiers::{EventId, RoomId, UserId};
@@ -23,7 +23,7 @@ ruma_event! {
             ///
             /// A mapping of event ID to a collection of receipts for this event ID. The event ID is the ID of
             /// the event being acknowledged and *not* an ID for the receipt itself.
-            HashMap<EventId, Receipts>
+            BTreeMap<EventId, Receipts>
         },
     }
 }
@@ -40,7 +40,7 @@ pub struct Receipts {
 /// A mapping of user ID to receipt.
 ///
 /// The user ID is the entity who sent this receipt.
-pub type UserReceipts = HashMap<UserId, Receipt>;
+pub type UserReceipts = BTreeMap<UserId, Receipt>;
 
 /// An acknowledgement of an event.
 #[derive(Clone, Debug, PartialEq, Deserialize, Serialize)]
diff --git a/src/room.rs b/src/room.rs
index 5b4e35a4..e05ee9ad 100644
--- a/src/room.rs
+++ b/src/room.rs
@@ -2,7 +2,7 @@
 //!
 //! This module also contains types shared by events in its child namespaces.
 
-use std::collections::HashMap;
+use std::collections::BTreeMap;
 
 use js_int::UInt;
 use serde::{Deserialize, Serialize};
@@ -97,7 +97,7 @@ pub struct EncryptedFile {
 
     /// A map from an algorithm name to a hash of the ciphertext, encoded as unpadded base64.
     /// Clients should support the SHA-256 hash, which uses the key sha256.
-    pub hashes: HashMap<String, String>,
+    pub hashes: BTreeMap<String, String>,
 
     /// Version of the encrypted attachments protocol. Must be `v2`.
     pub v: String,
diff --git a/src/room/canonical_alias.rs b/src/room/canonical_alias.rs
index 1753580e..f0d2cd48 100644
--- a/src/room/canonical_alias.rs
+++ b/src/room/canonical_alias.rs
@@ -1,6 +1,7 @@
 //! Types for the *m.room.canonical_alias* event.
 
 use std::{
+    collections::BTreeMap,
     convert::TryFrom,
     time::{SystemTime, UNIX_EPOCH},
 };
@@ -10,7 +11,7 @@ use serde::{
     ser::{Error, SerializeStruct},
     Deserialize, Serialize, Serializer,
 };
-use serde_json::{Map, Value};
+use serde_json::Value;
 
 use crate::{util::empty_string_as_none, Event, EventType, FromRaw};
 
@@ -39,7 +40,7 @@ pub struct CanonicalAliasEvent {
     pub state_key: String,
 
     /// Additional key-value pairs not signed by the homeserver.
-    pub unsigned: Map<String, Value>,
+    pub unsigned: BTreeMap<String, Value>,
 }
 
 /// The payload for `CanonicalAliasEvent`.
@@ -165,7 +166,7 @@ pub(crate) mod raw {
 
         /// Additional key-value pairs not signed by the homeserver.
         #[serde(default)]
-        pub unsigned: Map<String, Value>,
+        pub unsigned: BTreeMap<String, Value>,
     }
 
     /// The payload of a `CanonicalAliasEvent`.
@@ -185,12 +186,13 @@ pub(crate) mod raw {
 #[cfg(test)]
 mod tests {
     use std::{
+        collections::BTreeMap,
         convert::TryFrom,
         time::{Duration, UNIX_EPOCH},
     };
 
     use ruma_identifiers::{EventId, RoomAliasId, UserId};
-    use serde_json::{from_value as from_json_value, json, to_value as to_json_value, Map};
+    use serde_json::{from_value as from_json_value, json, to_value as to_json_value};
 
     use super::{CanonicalAliasEvent, CanonicalAliasEventContent};
     use crate::EventResult;
@@ -207,7 +209,7 @@ mod tests {
             room_id: None,
             sender: UserId::try_from("@carl:example.com").unwrap(),
             state_key: "".to_string(),
-            unsigned: Map::new(),
+            unsigned: BTreeMap::new(),
         };
 
         let actual = to_json_value(&canonical_alias_event).unwrap();
diff --git a/src/room/encrypted.rs b/src/room/encrypted.rs
index 5ebf4626..99b4020b 100644
--- a/src/room/encrypted.rs
+++ b/src/room/encrypted.rs
@@ -1,11 +1,11 @@
 //! Types for the *m.room.encrypted* event.
 
-use std::{collections::HashMap, time::SystemTime};
+use std::{collections::BTreeMap, time::SystemTime};
 
 use js_int::UInt;
 use ruma_identifiers::{DeviceId, EventId, RoomId, UserId};
 use serde::{Deserialize, Deserializer, Serialize, Serializer};
-use serde_json::{from_value, Map, Value};
+use serde_json::{from_value, Value};
 
 use crate::{Algorithm, EventType, FromRaw};
 
@@ -34,8 +34,8 @@ pub struct EncryptedEvent {
     pub sender: UserId,
 
     /// Additional key-value pairs not signed by the homeserver.
-    #[serde(skip_serializing_if = "Map::is_empty")]
-    pub unsigned: Map<String, Value>,
+    #[serde(skip_serializing_if = "BTreeMap::is_empty")]
+    pub unsigned: BTreeMap<String, Value>,
 }
 
 /// The payload for `EncryptedEvent`.
@@ -134,7 +134,7 @@ pub(crate) mod raw {
 
         /// Additional key-value pairs not signed by the homeserver.
         #[serde(default)]
-        pub unsigned: Map<String, Value>,
+        pub unsigned: BTreeMap<String, Value>,
     }
 
     /// The payload for `EncryptedEvent`.
@@ -206,7 +206,7 @@ pub struct OlmV1Curve25519AesSha2Content {
     pub algorithm: Algorithm,
 
     /// A map from the recipient Curve25519 identity key to ciphertext information.
-    pub ciphertext: HashMap<String, CiphertextInfo>,
+    pub ciphertext: BTreeMap<String, CiphertextInfo>,
 
     /// The Curve25519 key of the sender.
     pub sender_key: String,
diff --git a/src/room/member.rs b/src/room/member.rs
index 81433c1c..53dc1cde 100644
--- a/src/room/member.rs
+++ b/src/room/member.rs
@@ -1,6 +1,6 @@
 //! Types for the *m.room.member* event.
 
-use std::collections::HashMap;
+use std::collections::BTreeMap;
 
 use ruma_events_macros::ruma_event;
 use ruma_identifiers::UserId;
@@ -123,7 +123,7 @@ pub struct SignedContent {
 
     /// A single signature from the verifying server, in the format specified by the Signing Events
     /// section of the server-server API.
-    pub signatures: HashMap<String, HashMap<String, String>>,
+    pub signatures: BTreeMap<String, BTreeMap<String, String>>,
 
     /// The token property of the containing third_party_invite object.
     pub token: String,
@@ -227,7 +227,7 @@ mod tests {
     };
 
     use ruma_identifiers::{EventId, RoomId, UserId};
-    use serde_json::{json, Map};
+    use serde_json::json;
 
     use super::*;
     use crate::util::serde_json_eq_try_from_raw;
@@ -247,7 +247,7 @@ mod tests {
             room_id: Some(RoomId::try_from("!n8f893n9:example.com").unwrap()),
             sender: UserId::try_from("@carl:example.com").unwrap(),
             state_key: "example.com".to_string(),
-            unsigned: Map::new(),
+            unsigned: BTreeMap::new(),
             prev_content: None,
         };
         let json = json!({
@@ -279,7 +279,7 @@ mod tests {
             room_id: Some(RoomId::try_from("!n8f893n9:example.com").unwrap()),
             sender: UserId::try_from("@carl:example.com").unwrap(),
             state_key: "example.com".to_string(),
-            unsigned: Map::new(),
+            unsigned: BTreeMap::new(),
             prev_content: Some(MemberEventContent {
                 avatar_url: None,
                 displayname: None,
@@ -335,7 +335,7 @@ mod tests {
             room_id: Some(RoomId::try_from("!jEsUZKDJdhlrceRyVU:example.org").unwrap()),
             sender: UserId::try_from("@alice:example.org").unwrap(),
             state_key: "@alice:example.org".to_string(),
-            unsigned: Map::new(),
+            unsigned: BTreeMap::new(),
             prev_content: None,
         };
         let json = json!({
@@ -390,7 +390,7 @@ mod tests {
             room_id: Some(RoomId::try_from("!jEsUZKDJdhlrceRyVU:example.org").unwrap()),
             sender: UserId::try_from("@alice:example.org").unwrap(),
             state_key: "@alice:example.org".to_string(),
-            unsigned: Map::new(),
+            unsigned: BTreeMap::new(),
             prev_content: Some(MemberEventContent {
                 avatar_url: Some("mxc://example.org/SEsfnsuifSDFSSEF".to_owned()),
                 displayname: Some("Alice Margatroid".to_owned()),
diff --git a/src/room/message.rs b/src/room/message.rs
index 820723e9..c3083335 100644
--- a/src/room/message.rs
+++ b/src/room/message.rs
@@ -1,11 +1,11 @@
 //! Types for the *m.room.message* event.
 
-use std::time::SystemTime;
+use std::{collections::BTreeMap, time::SystemTime};
 
 use js_int::UInt;
 use ruma_identifiers::{EventId, RoomId, UserId};
 use serde::{ser::SerializeStruct, Deserialize, Deserializer, Serialize, Serializer};
-use serde_json::{from_value, Map, Value};
+use serde_json::{from_value, Value};
 
 use super::{EncryptedFile, ImageInfo, ThumbnailInfo};
 use crate::{EventType, FromRaw};
@@ -34,8 +34,8 @@ pub struct MessageEvent {
     pub sender: UserId,
 
     /// Additional key-value pairs not signed by the homeserver.
-    #[serde(skip_serializing_if = "Map::is_empty")]
-    pub unsigned: Map<String, Value>,
+    #[serde(skip_serializing_if = "BTreeMap::is_empty")]
+    pub unsigned: BTreeMap<String, Value>,
 }
 
 /// The payload for `MessageEvent`.
@@ -163,7 +163,7 @@ pub(crate) mod raw {
 
         /// Additional key-value pairs not signed by the homeserver.
         #[serde(default)]
-        pub unsigned: Map<String, Value>,
+        pub unsigned: BTreeMap<String, Value>,
     }
 
     /// The payload for `MessageEvent`.
diff --git a/src/room/name.rs b/src/room/name.rs
index 857acfb2..0fe4c54f 100644
--- a/src/room/name.rs
+++ b/src/room/name.rs
@@ -1,10 +1,10 @@
 //! Types for the *m.room.name* event.
 
-use std::time::SystemTime;
+use std::{collections::BTreeMap, time::SystemTime};
 
 use ruma_identifiers::{EventId, RoomId, UserId};
 use serde::{Deserialize, Serialize};
-use serde_json::{Map, Value};
+use serde_json::Value;
 
 use crate::{util::empty_string_as_none, EventType, InvalidInput, TryFromRaw};
 
@@ -37,8 +37,8 @@ pub struct NameEvent {
     pub state_key: String,
 
     /// Additional key-value pairs not signed by the homeserver.
-    #[serde(skip_serializing_if = "Map::is_empty")]
-    pub unsigned: Map<String, Value>,
+    #[serde(skip_serializing_if = "BTreeMap::is_empty")]
+    pub unsigned: BTreeMap<String, Value>,
 }
 
 /// The payload for `NameEvent`.
@@ -136,7 +136,7 @@ pub(crate) mod raw {
 
         /// Additional key-value pairs not signed by the homeserver.
         #[serde(default)]
-        pub unsigned: Map<String, Value>,
+        pub unsigned: BTreeMap<String, Value>,
     }
 
     /// The payload of a `NameEvent`.
@@ -154,13 +154,14 @@ pub(crate) mod raw {
 #[cfg(test)]
 mod tests {
     use std::{
+        collections::BTreeMap,
         convert::TryFrom,
         iter::FromIterator,
         time::{Duration, UNIX_EPOCH},
     };
 
     use ruma_identifiers::{EventId, RoomId, UserId};
-    use serde_json::{from_value as from_json_value, json, to_value as to_json_value, Map};
+    use serde_json::{from_value as from_json_value, json, to_value as to_json_value};
 
     use crate::EventResult;
 
@@ -178,7 +179,7 @@ mod tests {
             room_id: None,
             sender: UserId::try_from("@carl:example.com").unwrap(),
             state_key: "".to_string(),
-            unsigned: Map::new(),
+            unsigned: BTreeMap::new(),
         };
 
         let actual = to_json_value(&name_event).unwrap();
diff --git a/src/room/pinned_events.rs b/src/room/pinned_events.rs
index 631706f3..ec149691 100644
--- a/src/room/pinned_events.rs
+++ b/src/room/pinned_events.rs
@@ -17,10 +17,13 @@ ruma_event! {
 
 #[cfg(test)]
 mod tests {
-    use std::time::{Duration, UNIX_EPOCH};
+    use std::{
+        collections::BTreeMap,
+        time::{Duration, UNIX_EPOCH},
+    };
 
     use ruma_identifiers::{EventId, RoomId, UserId};
-    use serde_json::{to_string, Map};
+    use serde_json::to_string;
 
     use crate::{
         room::pinned_events::{PinnedEventsEvent, PinnedEventsEventContent},
@@ -42,7 +45,7 @@ mod tests {
             room_id: Some(RoomId::new("example.com").unwrap()),
             sender: UserId::new("example.com").unwrap(),
             state_key: "".to_string(),
-            unsigned: Map::new(),
+            unsigned: BTreeMap::new(),
         };
 
         let serialized_event = to_string(&event).unwrap();
diff --git a/src/room/power_levels.rs b/src/room/power_levels.rs
index 4b8a0705..e7ae8e1e 100644
--- a/src/room/power_levels.rs
+++ b/src/room/power_levels.rs
@@ -1,11 +1,11 @@
 //! Types for the *m.room.power_levels* event.
 
-use std::{collections::HashMap, time::SystemTime};
+use std::{collections::BTreeMap, time::SystemTime};
 
 use js_int::Int;
 use ruma_identifiers::{EventId, RoomId, UserId};
 use serde::{Deserialize, Serialize};
-use serde_json::{Map, Value};
+use serde_json::Value;
 
 use crate::{EventType, FromRaw};
 
@@ -32,8 +32,8 @@ pub struct PowerLevelsEvent {
     pub room_id: Option<RoomId>,
 
     /// Additional key-value pairs not signed by the homeserver.
-    #[serde(skip_serializing_if = "Map::is_empty")]
-    pub unsigned: Map<String, Value>,
+    #[serde(skip_serializing_if = "BTreeMap::is_empty")]
+    pub unsigned: BTreeMap<String, Value>,
 
     /// The unique identifier for the user who sent this event.
     pub sender: UserId,
@@ -52,8 +52,8 @@ pub struct PowerLevelsEventContent {
     /// The level required to send specific event types.
     ///
     /// This is a mapping from event type to power level required.
-    #[serde(skip_serializing_if = "HashMap::is_empty")]
-    pub events: HashMap<EventType, Int>,
+    #[serde(skip_serializing_if = "BTreeMap::is_empty")]
+    pub events: BTreeMap<EventType, Int>,
 
     /// The default level required to send message events.
     #[serde(skip_serializing_if = "is_power_level_zero")]
@@ -78,8 +78,8 @@ pub struct PowerLevelsEventContent {
     /// The power levels for specific users.
     ///
     /// This is a mapping from `user_id` to power level for that user.
-    #[serde(skip_serializing_if = "HashMap::is_empty")]
-    pub users: HashMap<UserId, Int>,
+    #[serde(skip_serializing_if = "BTreeMap::is_empty")]
+    pub users: BTreeMap<UserId, Int>,
 
     /// The default power level for every user in the room.
     #[serde(skip_serializing_if = "is_power_level_zero")]
@@ -158,7 +158,7 @@ pub(crate) mod raw {
 
         /// Additional key-value pairs not signed by the homeserver.
         #[serde(default)]
-        pub unsigned: Map<String, Value>,
+        pub unsigned: BTreeMap<String, Value>,
 
         /// The unique identifier for the user who sent this event.
         pub sender: UserId,
@@ -178,7 +178,7 @@ pub(crate) mod raw {
         ///
         /// This is a mapping from event type to power level required.
         #[serde(default)]
-        pub events: HashMap<EventType, Int>,
+        pub events: BTreeMap<EventType, Int>,
 
         /// The default level required to send message events.
         #[serde(default)]
@@ -204,7 +204,7 @@ pub(crate) mod raw {
         ///
         /// This is a mapping from `user_id` to power level for that user.
         #[serde(default)]
-        pub users: HashMap<UserId, Int>,
+        pub users: BTreeMap<UserId, Int>,
 
         /// The default power level for every user in the room.
         #[serde(default)]
@@ -263,15 +263,15 @@ fn is_power_level_zero(l: &Int) -> bool {
 #[cfg(test)]
 mod tests {
     use std::{
-        collections::HashMap,
+        collections::BTreeMap,
         convert::TryFrom,
         time::{Duration, UNIX_EPOCH},
     };
 
     use js_int::Int;
-    use maplit::hashmap;
+    use maplit::btreemap;
     use ruma_identifiers::{EventId, RoomId, UserId};
-    use serde_json::{json, to_value as to_json_value, Map};
+    use serde_json::{json, to_value as to_json_value};
 
     use super::{
         default_power_level, NotificationPowerLevels, PowerLevelsEvent, PowerLevelsEventContent,
@@ -285,13 +285,13 @@ mod tests {
         let power_levels_event = PowerLevelsEvent {
             content: PowerLevelsEventContent {
                 ban: default,
-                events: HashMap::new(),
+                events: BTreeMap::new(),
                 events_default: Int::from(0),
                 invite: default,
                 kick: default,
                 redact: default,
                 state_default: default,
-                users: HashMap::new(),
+                users: BTreeMap::new(),
                 users_default: Int::from(0),
                 notifications: NotificationPowerLevels::default(),
             },
@@ -299,7 +299,7 @@ mod tests {
             origin_server_ts: UNIX_EPOCH + Duration::from_millis(1),
             prev_content: None,
             room_id: None,
-            unsigned: Map::new(),
+            unsigned: BTreeMap::new(),
             sender: UserId::try_from("@carl:example.com").unwrap(),
             state_key: "".to_string(),
         };
@@ -323,7 +323,7 @@ mod tests {
         let power_levels_event = PowerLevelsEvent {
             content: PowerLevelsEventContent {
                 ban: Int::from(23),
-                events: hashmap! {
+                events: btreemap! {
                     EventType::Dummy => Int::from(23)
                 },
                 events_default: Int::from(23),
@@ -331,7 +331,7 @@ mod tests {
                 kick: Int::from(23),
                 redact: Int::from(23),
                 state_default: Int::from(23),
-                users: hashmap! {
+                users: btreemap! {
                     user.clone() => Int::from(23)
                 },
                 users_default: Int::from(23),
@@ -344,7 +344,7 @@ mod tests {
             prev_content: Some(PowerLevelsEventContent {
                 // Make just one field different so we at least know they're two different objects.
                 ban: Int::from(42),
-                events: hashmap! {
+                events: btreemap! {
                     EventType::Dummy => Int::from(42)
                 },
                 events_default: Int::from(42),
@@ -352,7 +352,7 @@ mod tests {
                 kick: Int::from(42),
                 redact: Int::from(42),
                 state_default: Int::from(42),
-                users: hashmap! {
+                users: btreemap! {
                     user.clone() => Int::from(42)
                 },
                 users_default: Int::from(42),
diff --git a/src/room/server_acl.rs b/src/room/server_acl.rs
index 130ccc4b..963f0071 100644
--- a/src/room/server_acl.rs
+++ b/src/room/server_acl.rs
@@ -1,10 +1,10 @@
 //! Types for the *m.room.server_acl* event.
 
-use std::time::SystemTime;
+use std::{collections::BTreeMap, time::SystemTime};
 
 use ruma_identifiers::{EventId, RoomId, UserId};
 use serde::{Deserialize, Serialize};
-use serde_json::{Map, Value};
+use serde_json::Value;
 
 use crate::{util::default_true, EventType, FromRaw};
 
@@ -37,8 +37,8 @@ pub struct ServerAclEvent {
     pub state_key: String,
 
     /// Additional key-value pairs not signed by the homeserver.
-    #[serde(skip_serializing_if = "Map::is_empty")]
-    pub unsigned: Map<String, Value>,
+    #[serde(skip_serializing_if = "BTreeMap::is_empty")]
+    pub unsigned: BTreeMap<String, Value>,
 }
 
 /// The payload for `ServerAclEvent`.
@@ -129,7 +129,7 @@ pub(crate) mod raw {
 
         /// Additional key-value pairs not signed by the homeserver.
         #[serde(default)]
-        pub unsigned: Map<String, Value>,
+        pub unsigned: BTreeMap<String, Value>,
 
         /// The unique identifier for the user who sent this event.
         pub sender: UserId,
diff --git a/src/tag.rs b/src/tag.rs
index 6c59d994..65b17517 100644
--- a/src/tag.rs
+++ b/src/tag.rs
@@ -1,6 +1,6 @@
 //! Types for the *m.tag* event.
 
-use std::collections::HashMap;
+use std::collections::BTreeMap;
 
 use ruma_events_macros::ruma_event;
 use serde::{Deserialize, Serialize};
@@ -12,7 +12,7 @@ ruma_event! {
         event_type: "m.tag",
         content: {
             /// A map of tag names to tag info.
-            pub tags: HashMap<String, TagInfo>,
+            pub tags: BTreeMap<String, TagInfo>,
         },
     }
 }
diff --git a/src/util.rs b/src/util.rs
index 5a6e8494..80bb7cc6 100644
--- a/src/util.rs
+++ b/src/util.rs
@@ -72,7 +72,7 @@ where
     }
 }
 
-/// Serde serialization and deserialization functions that map a `Vec<T>` to a `HashMap<T, Empty>`.
+/// Serde serialization and deserialization functions that map a `Vec<T>` to a `BTreeMap<T, Empty>`.
 ///
 /// The Matrix spec sometimes specifies lists as hash maps so the list entries can be expanded with
 /// attributes without breaking compatibility. As that would be a breaking change for ruma's event
@@ -80,28 +80,30 @@ where
 ///
 /// To be used as `#[serde(with = "vec_as_map_of_empty")]`.
 pub mod vec_as_map_of_empty {
-    use crate::Empty;
+    use std::collections::BTreeMap;
+
     use serde::{Deserialize, Deserializer, Serialize, Serializer};
-    use std::{collections::HashMap, hash::Hash};
+
+    use crate::Empty;
 
     #[allow(clippy::ptr_arg)]
     pub fn serialize<S, T>(vec: &Vec<T>, serializer: S) -> Result<S::Ok, S::Error>
     where
         S: Serializer,
-        T: Serialize + Hash + Eq,
+        T: Serialize + Eq + Ord,
     {
         vec.iter()
             .map(|v| (v, Empty))
-            .collect::<HashMap<_, _>>()
+            .collect::<BTreeMap<_, _>>()
             .serialize(serializer)
     }
 
     pub fn deserialize<'de, D, T>(deserializer: D) -> Result<Vec<T>, D::Error>
     where
         D: Deserializer<'de>,
-        T: Deserialize<'de> + Hash + Eq,
+        T: Deserialize<'de> + Eq + Ord,
     {
-        HashMap::<T, Empty>::deserialize(deserializer)
+        BTreeMap::<T, Empty>::deserialize(deserializer)
             .map(|hashmap| hashmap.into_iter().map(|(k, _)| k).collect())
     }
 }
diff --git a/tests/ruma_events_macros.rs b/tests/ruma_events_macros.rs
index a1061e98..a7742229 100644
--- a/tests/ruma_events_macros.rs
+++ b/tests/ruma_events_macros.rs
@@ -1,5 +1,5 @@
 use std::{
-    collections::HashMap,
+    collections::BTreeMap,
     convert::TryFrom,
     time::{Duration, UNIX_EPOCH},
 };
@@ -37,7 +37,7 @@ mod common_case {
             room_id: None,
             sender: UserId::try_from("@carl:example.com").unwrap(),
             state_key: "example.com".to_string(),
-            unsigned: serde_json::Map::new(),
+            unsigned: std::collections::BTreeMap::new(),
         };
         let json = json!({
             "content": {
@@ -66,7 +66,7 @@ mod common_case {
             room_id: Some(RoomId::try_from("!n8f893n9:example.com").unwrap()),
             sender: UserId::try_from("@carl:example.com").unwrap(),
             state_key: "example.com".to_string(),
-            unsigned: serde_json::Map::new(),
+            unsigned: std::collections::BTreeMap::new(),
         };
         let json = json!({
             "content": {
@@ -183,7 +183,7 @@ mod type_alias {
                 ///
                 /// A mapping of `UserId`'s to a collection of `RoomId`'s which are considered
                 /// *direct* for that particular user.
-                HashMap<ruma_identifiers::UserId, Vec<ruma_identifiers::RoomId>>
+                BTreeMap<ruma_identifiers::UserId, Vec<ruma_identifiers::RoomId>>
             }
         }
     }