diff --git a/androscalpel_serializer/src/annotation.rs b/androscalpel_serializer/src/annotation.rs
index 9d3ae2d..74208da 100644
--- a/androscalpel_serializer/src/annotation.rs
+++ b/androscalpel_serializer/src/annotation.rs
@@ -1,18 +1,69 @@
-use crate::{ReadSeek, Result, Serializable};
+use crate::{EncodedValue, Error, ReadSeek, Result, Serializable, Uleb128};
 use std::io::Write;
 
+// To derive Serializable
+use crate as androscalpel_serializer;
+
+/// Encoded Annotation https://source.android.com/docs/core/runtime/dex-format#encoded-annotation
 #[derive(Debug, Clone, PartialEq, Eq)]
-pub struct EncodedAnnotation;
+pub struct EncodedAnnotation {
+    /// Type of the annotation. This must be a class (not array or primitive) type.
+    pub type_idx: Uleb128, // TODO: check it's a class
+    //pub size: Uleb128,
+    pub elements: Vec<AnnotationElement>,
+}
+
+impl EncodedAnnotation {
+    /// Return the size field
+    pub fn size_field(&self) -> Uleb128 {
+        Uleb128(self.elements.len() as u32)
+    }
+}
+
+/// Annotation: https://source.android.com/docs/core/runtime/dex-format#annotation-element
+#[derive(Serializable, Debug, Clone, PartialEq, Eq)]
+pub struct AnnotationElement {
+    pub name_idx: Uleb128,
+    pub value: EncodedValue,
+}
 
 impl Serializable for EncodedAnnotation {
-    fn serialize(&self, _output: &mut dyn Write) -> Result<()> {
-        todo!()
+    fn serialize(&self, output: &mut dyn Write) -> Result<()> {
+        let Self { type_idx, elements } = self;
+        // Check if the element are sorted
+        if !elements.is_empty() {
+            let mut idx_0 = elements[0].name_idx;
+            for idx_1 in elements.iter().map(|elt| elt.name_idx).skip(1) {
+                if idx_0 > idx_1 {
+                    return Err(Error::SerializationError(format!(
+                        "Failed to serialize EncodedAnnotation: element must be sorted in increasing order by string_id index, found {idx_0:?} before {idx_1:?}"
+                    )));
+                }
+                idx_0 = idx_1;
+            }
+        }
+        type_idx.serialize(output)?;
+        self.size_field().serialize(output)?;
+        for elt in elements {
+            elt.serialize(output)?;
+        }
+        Ok(())
     }
-    fn deserialize(_input: &mut dyn ReadSeek) -> Result<Self> {
-        todo!()
+    fn deserialize(input: &mut dyn ReadSeek) -> Result<Self> {
+        let type_idx = Uleb128::deserialize(input)?;
+        let Uleb128(size) = Uleb128::deserialize(input)?;
+        let mut elements = vec![];
+        for _ in 0..size {
+            elements.push(AnnotationElement::deserialize(input)?);
+        }
+        Ok(Self { type_idx, elements })
     }
 
     fn size(&self) -> usize {
-        todo!()
+        self.type_idx.size()
+            + self.size_field().size()
+            + self.elements.iter().map(|val| val.size()).sum::<usize>()
     }
 }
+
+// TODO: add tests
diff --git a/androscalpel_serializer/src/array.rs b/androscalpel_serializer/src/array.rs
index ec9a327..44b7222 100644
--- a/androscalpel_serializer/src/array.rs
+++ b/androscalpel_serializer/src/array.rs
@@ -11,15 +11,15 @@ pub struct EncodedArray {
 
 impl EncodedArray {
     /// Return the size field
-    pub fn size(&self) -> Uleb128 {
+    pub fn size_field(&self) -> Uleb128 {
         Uleb128(self.values.len() as u32)
     }
 }
 
 impl Serializable for EncodedArray {
     fn serialize(&self, output: &mut dyn Write) -> Result<()> {
-        self.size().serialize(output)?;
-        for value in self.values {
+        self.size_field().serialize(output)?;
+        for value in &self.values {
             value.serialize(output)?;
         }
         Ok(())
@@ -38,6 +38,6 @@ impl Serializable for EncodedArray {
     }
 
     fn size(&self) -> usize {
-        self.size().size() + self.values.iter().map(|val| val.size()).sum::<usize>()
+        self.size_field().size() + self.values.iter().map(|val| val.size()).sum::<usize>()
     }
 }
diff --git a/androscalpel_serializer/src/core/leb.rs b/androscalpel_serializer/src/core/leb.rs
index 348d816..822b4dc 100644
--- a/androscalpel_serializer/src/core/leb.rs
+++ b/androscalpel_serializer/src/core/leb.rs
@@ -5,15 +5,15 @@ use std::io::Write;
 use crate::{Error, ReadSeek, Result, Serializable};
 
 /// Signed LEB128, variable-length
-#[derive(Debug, Clone, PartialEq, Eq)]
+#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord)]
 pub struct Sleb128(pub i32);
 
 /// Unsigned LEB128, variable-length
-#[derive(Debug, Clone, PartialEq, Eq)]
+#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord)]
 pub struct Uleb128(pub u32);
 
 /// Unsigned LEB128 plus 1, variable-length
-#[derive(Debug, Clone, PartialEq, Eq)]
+#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord)]
 pub struct Uleb128p1(pub u32);
 
 impl Sleb128 {