diff --git a/ipc/codegen/src/serialization.rs b/ipc/codegen/src/serialization.rs
index adcaaf2bf..bfaa8e7e0 100644
--- a/ipc/codegen/src/serialization.rs
+++ b/ipc/codegen/src/serialization.rs
@@ -301,6 +301,7 @@ fn binary_expr_variant(
 	let type_name = ::syntax::print::pprust::ty_to_string(&ty);
 
 	let variant_ident = variant.node.name;
+	let variant_index_ident = builder.id(format!("{}", variant_index));
 
 	match variant.node.data {
 		ast::VariantData::Unit(_) => {
@@ -310,7 +311,7 @@ fn binary_expr_variant(
 
 			Ok(BinaryArm {
 				size: quote_arm!(cx, $pat => { 0usize } ),
-				write: quote_arm!(cx, $pat => { Ok(()) } ),
+				write: quote_arm!(cx, $pat => { buffer[0] = $variant_index_ident; Ok(()) } ),
 				read: quote_arm!(cx, $pat => { } ),
 			})
 		},
@@ -336,11 +337,14 @@ fn binary_expr_variant(
 			));
 
 			let (size_expr, write_expr, read_expr) = (binary_expr.size, vec![binary_expr.write], binary_expr.read);
-
-			let variant_index_ident = builder.id(format!("{}", variant_index));
 			Ok(BinaryArm {
 				size: quote_arm!(cx, $pat => { $size_expr } ),
-				write: quote_arm!(cx, $pat => { buffer[0] = $variant_index_ident; let buffer = &mut buffer[1..]; $write_expr } ),
+				write: quote_arm!(cx,
+					$pat => {
+						buffer[0] = $variant_index_ident;
+						let buffer = &mut buffer[1..];
+						$write_expr
+				}),
 				read: quote_arm!(cx, $pat => { $read_expr } ),
 			})
 		}
@@ -369,7 +373,12 @@ fn binary_expr_variant(
 			let (size_expr, write_expr, read_expr) = (binary_expr.size, vec![binary_expr.write], binary_expr.read);
 			Ok(BinaryArm {
 				size: quote_arm!(cx, $pat => { $size_expr } ),
-				write: quote_arm!(cx, $pat => { $write_expr } ),
+				write: quote_arm!(cx,
+					$pat => {
+						buffer[0] = $variant_index_ident;
+						let buffer = &mut buffer[1..];
+						$write_expr
+				}),
 				read: quote_arm!(cx, $pat => { $read_expr } ),
 			})
 		},
diff --git a/ipc/rpc/src/binary.rs b/ipc/rpc/src/binary.rs
index 7f73c8242..02f0da954 100644
--- a/ipc/rpc/src/binary.rs
+++ b/ipc/rpc/src/binary.rs
@@ -27,6 +27,67 @@ pub trait BinaryConvertable : Sized {
 	fn to_bytes(&self, buffer: &mut [u8]) -> Result<(), BinaryConvertError>;
 
 	fn from_bytes(buffer: &[u8]) -> Result<Self, BinaryConvertError>;
+
+	fn from_empty_bytes() -> Result<Self, BinaryConvertError> {
+		Err(BinaryConvertError)
+	}
+
+	fn len_params() -> usize {
+		0
+	}
+}
+
+impl<T> BinaryConvertable for Option<T> where T: BinaryConvertable {
+	fn size(&self) -> usize {
+		match * self { None => 0, Some(ref val) => val.size() }
+	}
+
+	fn to_bytes(&self, buffer: &mut [u8]) -> Result<(), BinaryConvertError> {
+		match *self { None => Err(BinaryConvertError), Some(ref val) => val.to_bytes(buffer) }
+	}
+
+	fn from_bytes(buffer: &[u8]) -> Result<Self, BinaryConvertError> {
+		Ok(Some(try!(T::from_bytes(buffer))))
+	}
+
+	fn from_empty_bytes() -> Result<Self, BinaryConvertError> {
+		Ok(None)
+	}
+
+	fn len_params() -> usize {
+		1
+	}
+}
+
+impl<T> BinaryConvertable for Vec<T> where T: BinaryConvertable {
+	fn size(&self) -> usize {
+		match T::len_params() {
+			0 => mem::size_of::<T>() * self.len(),
+			_ => self.iter().fold(0usize, |acc, t| acc + t.size()),
+		}
+	}
+
+	fn to_bytes(&self, buffer: &mut [u8]) -> Result<(), BinaryConvertError> {
+		let mut offset = 0usize;
+		for (index, item) in self.iter().enumerate() {
+			let item_end = offset + item.size();
+			try!(item.to_bytes(&mut buffer[offset..item_end]));
+			offset = item_end;
+		}
+		Ok(())
+	}
+
+	fn from_bytes(buffer: &[u8]) -> Result<Self, BinaryConvertError> {
+		Err(BinaryConvertError)
+	}
+
+	fn from_empty_bytes() -> Result<Self, BinaryConvertError> {
+		Ok(Self::new())
+	}
+
+	fn len_params() -> usize {
+		1
+	}
 }
 
 macro_rules! binary_fixed_size {