diff --git a/wasm-ast/src/factory.rs b/wasm-ast/src/factory.rs
index 0742f7c..d4e3ee4 100644
--- a/wasm-ast/src/factory.rs
+++ b/wasm-ast/src/factory.rs
@@ -104,8 +104,8 @@ impl StatList {
 			store_type,
 			memory,
 			offset,
-			value: self.stack.pop(),
-			pointer: self.stack.pop(),
+			value: self.stack.pop().into(),
+			pointer: self.stack.pop().into(),
 		});
 
 		self.leak_memory_write(memory);
@@ -312,7 +312,7 @@ impl<'a> Factory<'a> {
 		let stat = match now.block_data {
 			BlockData::Forward { .. } | BlockData::Backward { .. } => Statement::Block(now.into()),
 			BlockData::If { .. } => Statement::If(If {
-				condition: self.target.stack.pop(),
+				condition: self.target.stack.pop().into(),
 				on_true: now.into(),
 				on_false: None,
 			}),
@@ -376,7 +376,7 @@ impl<'a> Factory<'a> {
 
 	fn add_call_indirect(&mut self, ty: usize, table: usize) {
 		let (num_param, num_result) = self.type_info.by_type_index(ty);
-		let index = self.target.stack.pop();
+		let index = self.target.stack.pop().into();
 		let param_list = self.target.stack.pop_len(num_param).collect();
 
 		self.target.leak_pre_call();
@@ -458,7 +458,7 @@ impl<'a> Factory<'a> {
 			Operator::BrIf { relative_depth } => {
 				let target = relative_depth.try_into().unwrap();
 				let data = Statement::BrIf(BrIf {
-					condition: self.target.stack.pop(),
+					condition: self.target.stack.pop().into(),
 					target: self.get_br_terminator(target),
 				});
 
@@ -466,7 +466,7 @@ impl<'a> Factory<'a> {
 				self.target.code.push(data);
 			}
 			Operator::BrTable { ref table } => {
-				let condition = self.target.stack.pop();
+				let condition = self.target.stack.pop().into();
 				let data = table
 					.targets()
 					.map(Result::unwrap)
@@ -532,7 +532,7 @@ impl<'a> Factory<'a> {
 				let var = local_index.try_into().unwrap();
 				let data = Statement::SetLocal(SetLocal {
 					var,
-					value: self.target.stack.pop(),
+					value: self.target.stack.pop().into(),
 				});
 
 				self.target.leak_local_write(var);
@@ -543,7 +543,7 @@ impl<'a> Factory<'a> {
 				let get = Expression::GetLocal(GetLocal { var });
 				let set = Statement::SetLocal(SetLocal {
 					var,
-					value: self.target.stack.pop(),
+					value: self.target.stack.pop().into(),
 				});
 
 				self.target.leak_local_write(var);
@@ -560,7 +560,7 @@ impl<'a> Factory<'a> {
 				let var = global_index.try_into().unwrap();
 				let data = Statement::SetGlobal(SetGlobal {
 					var,
-					value: self.target.stack.pop(),
+					value: self.target.stack.pop().into(),
 				});
 
 				self.target.leak_global_write(var);
diff --git a/wasm-ast/src/node.rs b/wasm-ast/src/node.rs
index 98a85e9..dba1975 100644
--- a/wasm-ast/src/node.rs
+++ b/wasm-ast/src/node.rs
@@ -849,7 +849,7 @@ impl Br {
 }
 
 pub struct BrTable {
-	pub(crate) condition: Expression,
+	pub(crate) condition: Box<Expression>,
 	pub(crate) data: Vec<Br>,
 	pub(crate) default: Br,
 }
@@ -908,7 +908,7 @@ impl Block {
 }
 
 pub struct BrIf {
-	pub(crate) condition: Expression,
+	pub(crate) condition: Box<Expression>,
 	pub(crate) target: Br,
 }
 
@@ -925,7 +925,7 @@ impl BrIf {
 }
 
 pub struct If {
-	pub(crate) condition: Expression,
+	pub(crate) condition: Box<Expression>,
 	pub(crate) on_true: Block,
 	pub(crate) on_false: Option<Block>,
 }
@@ -972,7 +972,7 @@ impl Call {
 
 pub struct CallIndirect {
 	pub(crate) table: usize,
-	pub(crate) index: Expression,
+	pub(crate) index: Box<Expression>,
 	pub(crate) result: Range<usize>,
 	pub(crate) param_list: Vec<Expression>,
 }
@@ -1001,7 +1001,7 @@ impl CallIndirect {
 
 pub struct SetTemporary {
 	pub(crate) var: usize,
-	pub(crate) value: Expression,
+	pub(crate) value: Box<Expression>,
 }
 
 impl SetTemporary {
@@ -1018,7 +1018,7 @@ impl SetTemporary {
 
 pub struct SetLocal {
 	pub(crate) var: usize,
-	pub(crate) value: Expression,
+	pub(crate) value: Box<Expression>,
 }
 
 impl SetLocal {
@@ -1035,7 +1035,7 @@ impl SetLocal {
 
 pub struct SetGlobal {
 	pub(crate) var: usize,
-	pub(crate) value: Expression,
+	pub(crate) value: Box<Expression>,
 }
 
 impl SetGlobal {
@@ -1054,8 +1054,8 @@ pub struct StoreAt {
 	pub(crate) store_type: StoreType,
 	pub(crate) memory: usize,
 	pub(crate) offset: u32,
-	pub(crate) pointer: Expression,
-	pub(crate) value: Expression,
+	pub(crate) pointer: Box<Expression>,
+	pub(crate) value: Box<Expression>,
 }
 
 impl StoreAt {
diff --git a/wasm-ast/src/stack.rs b/wasm-ast/src/stack.rs
index dfe97f1..1d79857 100644
--- a/wasm-ast/src/stack.rs
+++ b/wasm-ast/src/stack.rs
@@ -139,7 +139,7 @@ impl Stack {
 			let get = Expression::GetTemporary(GetTemporary { var });
 			let set = Statement::SetTemporary(SetTemporary {
 				var,
-				value: std::mem::replace(&mut old.data, get),
+				value: std::mem::replace(&mut old.data, get).into(),
 			});
 
 			self.capacity = self.capacity.max(var + 1);