diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 6ee57d56..5fb9aaa3 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -1,7 +1,8 @@
 on:
   push:
-    branches: [ staging, trying, master ]
+    branches: [ master ]
   pull_request:
+    branches: [ master ]
 
 name: Continuous integration
 
@@ -30,19 +31,32 @@ jobs:
             TARGET: x86_64-unknown-linux-gnu
 
     steps:
-      - uses: actions/checkout@v2
-      - uses: actions-rs/toolchain@v1
+      - uses: actions/checkout@v4
+
+      - uses: dtolnay/rust-toolchain@stable
         with:
-          profile: minimal
           toolchain: ${{ matrix.rust }}
           target: ${{ matrix.TARGET }}
-          override: true
-      - uses: actions-rs/cargo@v1
-        with:
-          command: build
-          args: --target=${{ matrix.TARGET }}
-      - uses: actions-rs/cargo@v1
+
+      - run: cargo build --target=${{ matrix.TARGET }}
+
+      - run: cargo test --target=${{ matrix.TARGET }} --all-features
         if: ${{ contains(matrix.TARGET, 'x86_64') }}
+
+  clippy:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: dtolnay/rust-toolchain@stable
         with:
-          command: test
-          args: --target=${{ matrix.TARGET }} --all-features
+          components: clippy
+
+      - run: cargo clippy
+
+  fmt:
+    name: Rustfmt
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: dtolnay/rust-toolchain@stable
+      - run: cargo fmt --all -- --check
diff --git a/.github/workflows/clippy.yml b/.github/workflows/clippy.yml
deleted file mode 100644
index adc3a6ed..00000000
--- a/.github/workflows/clippy.yml
+++ /dev/null
@@ -1,20 +0,0 @@
-on:
-  push:
-    branches: [ staging, trying, master ]
-  pull_request:
-
-name: Clippy check
-jobs:
-  clippy_check:
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v2
-      - uses: actions-rs/toolchain@v1
-        with:
-          profile: minimal
-          toolchain: stable
-          override: true
-          components: clippy
-      - uses: actions-rs/clippy-check@v1
-        with:
-          token: ${{ secrets.GITHUB_TOKEN }}
diff --git a/.github/workflows/rustfmt.yml b/.github/workflows/rustfmt.yml
deleted file mode 100644
index 9a55c002..00000000
--- a/.github/workflows/rustfmt.yml
+++ /dev/null
@@ -1,23 +0,0 @@
-on:
-  push:
-    branches: [ staging, trying, master ]
-  pull_request:
-
-name: Code formatting check
-
-jobs:
-  fmt:
-    name: Rustfmt
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v2
-      - uses: actions-rs/toolchain@v1
-        with:
-          profile: minimal
-          toolchain: stable
-          override: true
-          components: rustfmt
-      - uses: actions-rs/cargo@v1
-        with:
-          command: fmt
-          args: --all -- --check
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 13565f95..f0fa068f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -12,6 +12,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 - Support for optional package `defmt` which allows for easy conversion for
 error types when using tools like `probe-rs` for logging over debuggers.
 - Implement `Serializer::collect_str`
+- Derive `Serialize` for `de::Error` and `ser::Error`
 
 ### Changed
 
diff --git a/rust-toolchain b/rust-toolchain
deleted file mode 100644
index 2bf5ad04..00000000
--- a/rust-toolchain
+++ /dev/null
@@ -1 +0,0 @@
-stable
diff --git a/src/ser/map.rs b/src/ser/map.rs
index 8e010c75..fe17a1f2 100644
--- a/src/ser/map.rs
+++ b/src/ser/map.rs
@@ -22,9 +22,9 @@ impl<'a, 'b: 'a> ser::SerializeMap for SerializeMap<'a, 'b> {
         Ok(())
     }
 
-    fn serialize_key<T: ?Sized>(&mut self, key: &T) -> Result<()>
+    fn serialize_key<T>(&mut self, key: &T) -> Result<()>
     where
-        T: ser::Serialize,
+        T: ser::Serialize + ?Sized,
     {
         if !self.first {
             self.ser.push(b',')?;
@@ -35,9 +35,9 @@ impl<'a, 'b: 'a> ser::SerializeMap for SerializeMap<'a, 'b> {
         Ok(())
     }
 
-    fn serialize_value<T: ?Sized>(&mut self, value: &T) -> Result<()>
+    fn serialize_value<T>(&mut self, value: &T) -> Result<()>
     where
-        T: ser::Serialize,
+        T: ser::Serialize + ?Sized,
     {
         value.serialize(&mut *self.ser)?;
         Ok(())
diff --git a/src/ser/mod.rs b/src/ser/mod.rs
index aafeb0f0..977509d7 100644
--- a/src/ser/mod.rs
+++ b/src/ser/mod.rs
@@ -4,8 +4,8 @@ use core::mem::MaybeUninit;
 use core::{fmt, str};
 
 use serde::ser;
-use serde::Serialize;
 use serde::ser::SerializeStruct as _;
+use serde::Serialize;
 
 #[cfg(feature = "heapless")]
 use heapless::{String, Vec};
@@ -186,8 +186,8 @@ macro_rules! serialize_unsigned {
 macro_rules! serialize_signed {
     ($self:ident, $N:expr, $v:expr, $ixx:ident, $uxx:ident) => {{
         let v = $v;
-        let (signed, mut v) = if v == $ixx::min_value() {
-            (true, $ixx::max_value() as $uxx + 1)
+        let (signed, mut v) = if v == $ixx::MIN {
+            (true, $ixx::MAX as $uxx + 1)
         } else if v < 0 {
             (true, -v as $uxx)
         } else {
@@ -339,9 +339,9 @@ impl<'a, 'b: 'a> ser::Serializer for &'a mut Serializer<'b> {
         self.extend_from_slice(b"null")
     }
 
-    fn serialize_some<T: ?Sized>(self, value: &T) -> Result<Self::Ok>
+    fn serialize_some<T>(self, value: &T) -> Result<Self::Ok>
     where
-        T: ser::Serialize,
+        T: ser::Serialize + ?Sized,
     {
         value.serialize(self)
     }
@@ -363,14 +363,14 @@ impl<'a, 'b: 'a> ser::Serializer for &'a mut Serializer<'b> {
         self.serialize_str(variant)
     }
 
-    fn serialize_newtype_struct<T: ?Sized>(self, _name: &'static str, value: &T) -> Result<Self::Ok>
+    fn serialize_newtype_struct<T>(self, _name: &'static str, value: &T) -> Result<Self::Ok>
     where
-        T: ser::Serialize,
+        T: ser::Serialize + ?Sized,
     {
         value.serialize(self)
     }
 
-    fn serialize_newtype_variant<T: ?Sized>(
+    fn serialize_newtype_variant<T>(
         self,
         _name: &'static str,
         _variant_index: u32,
@@ -378,7 +378,7 @@ impl<'a, 'b: 'a> ser::Serializer for &'a mut Serializer<'b> {
         value: &T,
     ) -> Result<Self::Ok>
     where
-        T: ser::Serialize,
+        T: ser::Serialize + ?Sized,
     {
         self.push(b'{')?;
         let mut s = SerializeStruct::new(self);
@@ -441,9 +441,9 @@ impl<'a, 'b: 'a> ser::Serializer for &'a mut Serializer<'b> {
         Ok(SerializeStructVariant::new(self))
     }
 
-    fn collect_str<T: ?Sized>(self, value: &T) -> Result<Self::Ok>
+    fn collect_str<T>(self, value: &T) -> Result<Self::Ok>
     where
-        T: fmt::Display,
+        T: fmt::Display + ?Sized,
     {
         self.push(b'"')?;
 
@@ -715,7 +715,7 @@ mod tests {
 
         assert_eq!(
             &*crate::to_string::<_, N>(&Temperature {
-                temperature: -2.3456789012345e-23
+                temperature: -2.345_678_8e-23
             })
             .unwrap(),
             r#"{"temperature":-2.3456788e-23}"#
@@ -871,7 +871,7 @@ mod tests {
             {
                 let mut aux: String<{ N }> = String::new();
                 write!(aux, "{:.2}", self.0).unwrap();
-                serializer.serialize_bytes(&aux.as_bytes())
+                serializer.serialize_bytes(aux.as_bytes())
             }
         }
 
@@ -881,7 +881,7 @@ mod tests {
         let sd2 = SimpleDecimal(0.000);
         assert_eq!(&*crate::to_string::<_, N>(&sd2).unwrap(), r#"0.00"#);
 
-        let sd3 = SimpleDecimal(22222.777777);
+        let sd3 = SimpleDecimal(22_222.777);
         assert_eq!(&*crate::to_string::<_, N>(&sd3).unwrap(), r#"22222.78"#);
     }
 }
diff --git a/src/ser/seq.rs b/src/ser/seq.rs
index 7a4c4943..f4f799c1 100644
--- a/src/ser/seq.rs
+++ b/src/ser/seq.rs
@@ -17,9 +17,9 @@ impl<'a, 'b: 'a> ser::SerializeSeq for SerializeSeq<'a, 'b> {
     type Ok = ();
     type Error = Error;
 
-    fn serialize_element<T: ?Sized>(&mut self, value: &T) -> Result<()>
+    fn serialize_element<T>(&mut self, value: &T) -> Result<()>
     where
-        T: ser::Serialize,
+        T: ser::Serialize + ?Sized,
     {
         if !self.first {
             self.de.push(b',')?;
@@ -40,9 +40,9 @@ impl<'a, 'b: 'a> ser::SerializeTuple for SerializeSeq<'a, 'b> {
     type Ok = ();
     type Error = Error;
 
-    fn serialize_element<T: ?Sized>(&mut self, value: &T) -> Result<()>
+    fn serialize_element<T>(&mut self, value: &T) -> Result<()>
     where
-        T: ser::Serialize,
+        T: ser::Serialize + ?Sized,
     {
         ser::SerializeSeq::serialize_element(self, value)
     }
@@ -56,9 +56,9 @@ impl<'a, 'b: 'a> ser::SerializeTupleStruct for SerializeSeq<'a, 'b> {
     type Ok = ();
     type Error = Error;
 
-    fn serialize_field<T: ?Sized>(&mut self, value: &T) -> Result<()>
+    fn serialize_field<T>(&mut self, value: &T) -> Result<()>
     where
-        T: ser::Serialize,
+        T: ser::Serialize + ?Sized,
     {
         ser::SerializeSeq::serialize_element(self, value)
     }
diff --git a/src/ser/struct_.rs b/src/ser/struct_.rs
index a6c31a8c..6a35d347 100644
--- a/src/ser/struct_.rs
+++ b/src/ser/struct_.rs
@@ -17,9 +17,9 @@ impl<'a, 'b: 'a> ser::SerializeStruct for SerializeStruct<'a, 'b> {
     type Ok = ();
     type Error = Error;
 
-    fn serialize_field<T: ?Sized>(&mut self, key: &'static str, value: &T) -> Result<()>
+    fn serialize_field<T>(&mut self, key: &'static str, value: &T) -> Result<()>
     where
-        T: ser::Serialize,
+        T: ser::Serialize + ?Sized,
     {
         // XXX if `value` is `None` we not produce any output for this field
         if !self.first {
@@ -57,9 +57,9 @@ impl<'a, 'b: 'a> ser::SerializeStructVariant for SerializeStructVariant<'a, 'b>
     type Ok = ();
     type Error = Error;
 
-    fn serialize_field<T: ?Sized>(&mut self, key: &'static str, value: &T) -> Result<()>
+    fn serialize_field<T>(&mut self, key: &'static str, value: &T) -> Result<()>
     where
-        T: ser::Serialize,
+        T: ser::Serialize + ?Sized,
     {
         // XXX if `value` is `None` we not produce any output for this field
         if !self.first {