diff --git a/ruma-events-macros/tests/ruma_events_macros.rs b/ruma-events-macros/tests/ruma_events_macros.rs
index 16508be1..9548b3ec 100644
--- a/ruma-events-macros/tests/ruma_events_macros.rs
+++ b/ruma-events-macros/tests/ruma_events_macros.rs
@@ -1,16 +1,16 @@
 use std::{
+    borrow::Cow,
     convert::Infallible,
     fmt::{Debug, Display, Formatter, Result as FmtResult},
 };
 
-use serde::{
-    de::{DeserializeOwned, Error as SerdeError, Visitor},
-    Deserialize, Deserializer, Serialize, Serializer,
-};
+use serde::{de::DeserializeOwned, Deserialize, Deserializer, Serialize};
 use serde_json::Value;
 
 /// The type of an event.
-#[derive(Clone, Debug, PartialEq)]
+#[derive(Clone, Debug, PartialEq, Serialize, Deserialize)]
+// Cow<str> because deserialization sometimes needs to copy to unescape things
+#[serde(from = "Cow<'_, str>", into = "String")]
 pub enum EventType {
     /// m.direct
     Direct,
@@ -38,49 +38,26 @@ impl Display for EventType {
     }
 }
 
-impl<'a> From<&str> for EventType {
-    fn from(s: &str) -> EventType {
-        match s {
+impl<'a> From<Cow<'a, str>> for EventType {
+    fn from(s: Cow<'a, str>) -> EventType {
+        match &s as &str {
             "m.direct" => EventType::Direct,
             "m.room.aliases" => EventType::RoomAliases,
             "m.room.redaction" => EventType::RoomRedaction,
-            event_type => EventType::Custom(event_type.to_string()),
+            _ => EventType::Custom(s.into_owned()),
         }
     }
 }
 
-impl Serialize for EventType {
-    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
-    where
-        S: Serializer,
-    {
-        serializer.serialize_str(&self.to_string())
+impl From<&str> for EventType {
+    fn from(s: &str) -> EventType {
+        EventType::from(Cow::Borrowed(s))
     }
 }
 
-impl<'de> Deserialize<'de> for EventType {
-    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
-    where
-        D: Deserializer<'de>,
-    {
-        struct EventTypeVisitor;
-
-        impl<'de> Visitor<'de> for EventTypeVisitor {
-            type Value = EventType;
-
-            fn expecting(&self, formatter: &mut Formatter<'_>) -> FmtResult {
-                write!(formatter, "a Matrix event type as a string")
-            }
-
-            fn visit_str<E>(self, v: &str) -> Result<Self::Value, E>
-            where
-                E: SerdeError,
-            {
-                Ok(EventType::from(v))
-            }
-        }
-
-        deserializer.deserialize_str(EventTypeVisitor)
+impl From<EventType> for String {
+    fn from(event_type: EventType) -> String {
+        event_type.to_string()
     }
 }
 
diff --git a/src/key/verification/cancel.rs b/src/key/verification/cancel.rs
index c281c0b7..41d88553 100644
--- a/src/key/verification/cancel.rs
+++ b/src/key/verification/cancel.rs
@@ -1,12 +1,12 @@
 //! Types for the *m.key.verification.cancel* event.
 
-use std::fmt::{Display, Formatter, Result as FmtResult};
+use std::{
+    borrow::Cow,
+    fmt::{Display, Formatter, Result as FmtResult},
+};
 
 use ruma_events_macros::ruma_event;
-use serde::{
-    de::{Error as SerdeError, Visitor},
-    Deserialize, Deserializer, Serialize, Serializer,
-};
+use serde::{Deserialize, Serialize};
 
 ruma_event! {
     /// Cancels a key verification process/request.
@@ -33,7 +33,9 @@ ruma_event! {
 /// An error code for why the process/request was cancelled by the user.
 ///
 /// Custom error codes should use the Java package naming convention.
-#[derive(Clone, Debug, PartialEq)]
+#[derive(Clone, Debug, PartialEq, Serialize, Deserialize)]
+// Cow<str> because deserialization sometimes needs to copy to unescape things
+#[serde(from = "Cow<'_, str>", into = "String")]
 pub enum CancelCode {
     /// The user cancelled the verification.
     User,
@@ -101,9 +103,9 @@ impl Display for CancelCode {
     }
 }
 
-impl<'a> From<&str> for CancelCode {
-    fn from(s: &str) -> CancelCode {
-        match s {
+impl From<Cow<'_, str>> for CancelCode {
+    fn from(s: Cow<'_, str>) -> CancelCode {
+        match &s as &str {
             "m.user" => CancelCode::User,
             "m.timeout" => CancelCode::Timeout,
             "m.unknown_transaction" => CancelCode::UnknownTransaction,
@@ -113,43 +115,20 @@ impl<'a> From<&str> for CancelCode {
             "m.user_mismatch" => CancelCode::UserMismatch,
             "m.invalid_message" => CancelCode::InvalidMessage,
             "m.accepted" => CancelCode::Accepted,
-            cancel_code => CancelCode::Custom(cancel_code.to_string()),
+            _ => CancelCode::Custom(s.into_owned()),
         }
     }
 }
 
-impl Serialize for CancelCode {
-    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
-    where
-        S: Serializer,
-    {
-        serializer.serialize_str(&self.to_string())
+impl From<&str> for CancelCode {
+    fn from(s: &str) -> CancelCode {
+        CancelCode::from(Cow::Borrowed(s))
     }
 }
 
-impl<'de> Deserialize<'de> for CancelCode {
-    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
-    where
-        D: Deserializer<'de>,
-    {
-        struct CancelCodeVisitor;
-
-        impl<'de> Visitor<'de> for CancelCodeVisitor {
-            type Value = CancelCode;
-
-            fn expecting(&self, formatter: &mut Formatter<'_>) -> FmtResult {
-                write!(formatter, "an `m.key.verification.cancel` code as a string")
-            }
-
-            fn visit_str<E>(self, v: &str) -> Result<Self::Value, E>
-            where
-                E: SerdeError,
-            {
-                Ok(CancelCode::from(v))
-            }
-        }
-
-        deserializer.deserialize_str(CancelCodeVisitor)
+impl From<CancelCode> for String {
+    fn from(cancel_code: CancelCode) -> String {
+        cancel_code.to_string()
     }
 }
 
diff --git a/src/lib.rs b/src/lib.rs
index 039cf093..80258530 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -115,6 +115,7 @@
 #![allow(clippy::use_self)]
 
 use std::{
+    borrow::Cow,
     convert::Infallible,
     error::Error,
     fmt::{Debug, Display, Error as FmtError, Formatter, Result as FmtResult},
@@ -123,7 +124,7 @@ use std::{
 use js_int::UInt;
 use ruma_identifiers::{EventId, RoomId, UserId};
 use serde::{
-    de::{DeserializeOwned, Error as SerdeError, MapAccess, Visitor},
+    de::{DeserializeOwned, MapAccess, Visitor},
     ser::SerializeMap,
     Deserialize, Deserializer, Serialize, Serializer,
 };
@@ -376,7 +377,9 @@ impl<'de> Deserialize<'de> for Empty {
 }
 
 /// The type of an event.
-#[derive(Clone, Debug, Eq, Hash, PartialEq)]
+#[derive(Clone, Debug, Eq, Hash, PartialEq, Serialize, Deserialize)]
+// Cow<str> because deserialization sometimes needs to copy to unescape things
+#[serde(from = "Cow<'_, str>", into = "String")]
 pub enum EventType {
     /// m.call.answer
     CallAnswer,
@@ -666,9 +669,9 @@ impl Display for EventType {
     }
 }
 
-impl<'a> From<&str> for EventType {
-    fn from(s: &str) -> EventType {
-        match s {
+impl From<Cow<'_, str>> for EventType {
+    fn from(s: Cow<'_, str>) -> EventType {
+        match &s as &str {
             "m.call.answer" => EventType::CallAnswer,
             "m.call.candidates" => EventType::CallCandidates,
             "m.call.hangup" => EventType::CallHangup,
@@ -712,48 +715,27 @@ impl<'a> From<&str> for EventType {
             "m.sticker" => EventType::Sticker,
             "m.tag" => EventType::Tag,
             "m.typing" => EventType::Typing,
-            event_type => EventType::Custom(event_type.to_string()),
+            _ => EventType::Custom(s.into_owned()),
         }
     }
 }
 
-impl Serialize for EventType {
-    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
-    where
-        S: Serializer,
-    {
-        serializer.serialize_str(&self.to_string())
+impl<'a> From<&str> for EventType {
+    fn from(s: &str) -> EventType {
+        EventType::from(Cow::Borrowed(s))
     }
 }
 
-impl<'de> Deserialize<'de> for EventType {
-    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
-    where
-        D: Deserializer<'de>,
-    {
-        struct EventTypeVisitor;
-
-        impl<'de> Visitor<'de> for EventTypeVisitor {
-            type Value = EventType;
-
-            fn expecting(&self, formatter: &mut Formatter<'_>) -> FmtResult {
-                write!(formatter, "a Matrix event type as a string")
-            }
-
-            fn visit_str<E>(self, v: &str) -> Result<Self::Value, E>
-            where
-                E: SerdeError,
-            {
-                Ok(EventType::from(v))
-            }
-        }
-
-        deserializer.deserialize_str(EventTypeVisitor)
+impl From<EventType> for String {
+    fn from(event_type: EventType) -> String {
+        event_type.to_string()
     }
 }
 
 /// An encryption algorithm to be used to encrypt messages sent to a room.
-#[derive(Clone, Debug, PartialEq)]
+#[derive(Clone, Debug, PartialEq, Serialize, Deserialize)]
+// Cow<str> because deserialization sometimes needs to copy to unescape things
+#[serde(from = "Cow<'_, str>", into = "String")]
 pub enum Algorithm {
     /// Olm version 1 using Curve25519, AES-256, and SHA-256.
     OlmV1Curve25519AesSha2,
@@ -785,48 +767,25 @@ impl Display for Algorithm {
     }
 }
 
-impl<'a> From<&str> for Algorithm {
-    fn from(s: &str) -> Algorithm {
-        match s {
+impl From<Cow<'_, str>> for Algorithm {
+    fn from(s: Cow<'_, str>) -> Algorithm {
+        match &s as &str {
             "m.olm.v1.curve25519-aes-sha2" => Algorithm::OlmV1Curve25519AesSha2,
             "m.megolm.v1.aes-sha2" => Algorithm::MegolmV1AesSha2,
-            algorithm => Algorithm::Custom(algorithm.to_string()),
+            _ => Algorithm::Custom(s.into_owned()),
         }
     }
 }
 
-impl Serialize for Algorithm {
-    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
-    where
-        S: Serializer,
-    {
-        serializer.serialize_str(&self.to_string())
+impl From<&str> for Algorithm {
+    fn from(s: &str) -> Algorithm {
+        Algorithm::from(Cow::Borrowed(s))
     }
 }
 
-impl<'de> Deserialize<'de> for Algorithm {
-    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
-    where
-        D: Deserializer<'de>,
-    {
-        struct CancelCodeVisitor;
-
-        impl<'de> Visitor<'de> for CancelCodeVisitor {
-            type Value = Algorithm;
-
-            fn expecting(&self, formatter: &mut Formatter<'_>) -> FmtResult {
-                write!(formatter, "an encryption algorithm code as a string")
-            }
-
-            fn visit_str<E>(self, v: &str) -> Result<Self::Value, E>
-            where
-                E: SerdeError,
-            {
-                Ok(Algorithm::from(v))
-            }
-        }
-
-        deserializer.deserialize_str(CancelCodeVisitor)
+impl From<Algorithm> for String {
+    fn from(algorithm: Algorithm) -> String {
+        algorithm.to_string()
     }
 }