diff --git a/codegen/src/abi.rs b/codegen/src/abi.rs
index 5b8362071..aa39b7822 100644
--- a/codegen/src/abi.rs
+++ b/codegen/src/abi.rs
@@ -92,6 +92,7 @@ macro_rules! offset {
 
 offset! {
     (usize, 8),
+    (u64, 8),
     (i64, 8),
     (i32, 4),
     (u32, 4),
diff --git a/codegen/src/asm.rs b/codegen/src/asm.rs
index 392fb86e7..f1c5f876d 100644
--- a/codegen/src/asm.rs
+++ b/codegen/src/asm.rs
@@ -97,7 +97,7 @@ impl Assembler {
     /// Mock the stack input and output for checking
     /// the stack usages.
     pub fn emit_op(&mut self, opcode: OpCode) -> Result<()> {
-        tracing::trace!("stack length: {:?}", self.sp);
+        // tracing::trace!("stack length: {:?}", self.sp);
         tracing::trace!("emit opcode: {:?}", opcode);
         self.decrement_sp(opcode.stack_in() as u8)?;
         self.emit(opcode.into());
diff --git a/codegen/src/codegen.rs b/codegen/src/codegen.rs
index ab0f684df..5729874dd 100644
--- a/codegen/src/codegen.rs
+++ b/codegen/src/codegen.rs
@@ -59,7 +59,7 @@ impl CodeGen {
             // STACK: PC + params
             codegen.masm.increment_sp(1 + params_count)?;
             codegen.masm._jumpdest()?;
-            codegen.masm.shift_pc(params_count, true)?;
+            codegen.masm.shift_stack(params_count, true)?;
         }
 
         Ok(codegen)
diff --git a/codegen/src/dispatcher.rs b/codegen/src/dispatcher.rs
index a47b51ea8..0410a41a3 100644
--- a/codegen/src/dispatcher.rs
+++ b/codegen/src/dispatcher.rs
@@ -1,6 +1,8 @@
 //! Code generator for EVM dispatcher.
 
-use crate::{code::ExtFunc, DataSet, Error, Exports, Imports, JumpTable, MacroAssembler, Result};
+use crate::{
+    code::ExtFunc, DataSet, Error, Exports, Imports, JumpTable, MacroAssembler, Result, ToLSBytes,
+};
 use std::{
     collections::BTreeMap,
     ops::{Deref, DerefMut},
@@ -179,15 +181,14 @@ impl<'d> Dispatcher<'d> {
     }
 
     /// Emit return of ext function.
-    fn ext_return(&mut self, func: u32) -> Result<()> {
-        let sig = self
-            .funcs
-            .get(&func)
-            .ok_or(Error::FuncNotFound(func))?
-            .sig()?;
-
+    fn ext_return(&mut self, sig: &FuncType) -> Result<()> {
+        self.asm.increment_sp(1)?;
         let asm = self.asm.clone();
-        self.asm.main_return(sig.results())?;
+
+        {
+            self.asm.main_return(sig.results())?;
+        }
+
         let bytecode = {
             let jumpdest = vec![0x5b];
             let ret = self.asm.buffer()[asm.buffer().len()..].to_vec();
@@ -204,6 +205,52 @@ impl<'d> Dispatcher<'d> {
         Ok(())
     }
 
+    // Process to the selected function.
+    //
+    // 1. drop selector.
+    // 2. load calldata to stack.
+    // 3. jump to the callee function.
+    fn process(&mut self, sig: &FuncType) -> Result<()> {
+        self.asm.increment_sp(1)?;
+        let asm = self.asm.clone();
+        let len = sig.params().len() as u8;
+
+        {
+            // TODO: check the safety of this.
+            //
+            // [ callee, ret, selector ] -> [ selector, callee, ret ]
+            self.asm.shift_stack(2, false)?;
+            // [ selector, callee, ret ] -> [ callee, ret ]
+            self.asm._drop()?;
+            // [ callee, ret ] -> [ param * len, callee, ret ]
+            for p in (0..len).rev() {
+                let offset = 4 + p * 32;
+                self.asm.push(&offset.to_ls_bytes())?;
+                self.asm._calldataload()?;
+            }
+
+            // [ param * len, callee, ret ] -> [ ret, param * len, callee ]
+            self.asm.shift_stack(len + 1, false)?;
+            // [ ret, param * len, callee ] -> [ callee, ret, param * len ]
+            self.asm.shift_stack(len + 1, false)?;
+            self.asm._jump()?;
+        }
+
+        let bytecode = {
+            let jumpdest = vec![0x5b];
+            let ret = self.asm.buffer()[asm.buffer().len()..].to_vec();
+            [jumpdest, ret].concat()
+        };
+        *self.asm = asm;
+        let ret = ExtFunc {
+            bytecode,
+            stack_in: len,
+            stack_out: 1,
+        };
+        self.table.ext(self.asm.pc_offset(), ret);
+        Ok(())
+    }
+
     /// Emit selector to buffer.
     fn emit_selector(&mut self, selector: &Function<'_>, last: bool) -> Result<()> {
         let abi = self.load_abi(selector)?;
@@ -216,27 +263,40 @@ impl<'d> Dispatcher<'d> {
         );
 
         let func = self.query_func(&abi.name)?;
+        let sig = self
+            .funcs
+            .get(&func)
+            .ok_or(Error::FuncNotFound(func))?
+            .sig()?;
 
         // Jump to the end of the current function.
         //
         // TODO: detect the bytes of the position. (#157)
-        self.asm.increment_sp(1)?;
-        self.ext_return(func)?;
+        self.ext_return(&sig)?;
+
+        // Prepare the `PC` of the callee function.
+        {
+            // TODO: remove this (#160)
+            self.asm._jumpdest()?;
+            self.asm.increment_sp(1)?;
+            self.table.call(self.asm.pc_offset(), func);
+        }
 
         if !last {
-            self.asm._dup2()?;
+            self.asm._dup3()?;
         } else {
-            self.asm._swap1()?;
+            self.asm._swap2()?;
         }
 
         self.asm.push(&selector_bytes)?;
         self.asm._eq()?;
-        self.asm.increment_sp(1)?;
-
-        self.table.call(self.asm.pc_offset(), func);
+        self.process(&sig)?;
         self.asm._jumpi()?;
 
         if !last {
+            // drop the PC of the previous callee function.
+            self.asm._drop()?;
+            // drop the PC of the previous callee function preprocessor.
             self.asm._drop()?;
         }
 
diff --git a/codegen/src/import.rs b/codegen/src/import.rs
index 001c245be..a44eb6789 100644
--- a/codegen/src/import.rs
+++ b/codegen/src/import.rs
@@ -4,7 +4,7 @@ use std::{
     ops::{Deref, DerefMut},
 };
 
-use crate::{Error, MacroAssembler, Result};
+use crate::{Error, Result};
 
 /// EVM built-in function.
 #[derive(Clone, Copy, Debug, PartialOrd, Ord, PartialEq, Eq, Hash)]
@@ -61,14 +61,6 @@ impl Func {
             _ => 0,
         }
     }
-
-    /// Pre-processing for the function.
-    pub fn prelude(&self, masm: &mut MacroAssembler) -> Result<()> {
-        match self {
-            Self::Sstore => masm._swap1(),
-            _ => Ok(()),
-        }
-    }
 }
 
 impl TryFrom<(&str, &str)> for Func {
diff --git a/codegen/src/masm/mod.rs b/codegen/src/masm/mod.rs
index b273712d3..1dc995765 100644
--- a/codegen/src/masm/mod.rs
+++ b/codegen/src/masm/mod.rs
@@ -193,7 +193,7 @@ impl MacroAssembler {
     /// Shift the program counter to the bottom or the top of the
     /// parameters. This is used by the callee function for jumping
     /// back to the caller function.
-    pub fn shift_pc(&mut self, count: u8, from_top: bool) -> Result<()> {
+    pub fn shift_stack(&mut self, count: u8, from_top: bool) -> Result<()> {
         let mut swaps = 0;
 
         if from_top {
diff --git a/codegen/src/masm/ret.rs b/codegen/src/masm/ret.rs
index 811e519e1..2c9626289 100644
--- a/codegen/src/masm/ret.rs
+++ b/codegen/src/masm/ret.rs
@@ -46,7 +46,7 @@ impl MacroAssembler {
         }
 
         // TODO: handle the length of results > u8::MAX.
-        self.shift_pc(len, false)?;
+        self.shift_stack(len, false)?;
         self._jump()
     }
 }
diff --git a/codegen/src/visitor/call.rs b/codegen/src/visitor/call.rs
index 63feb97a7..fea2c2083 100644
--- a/codegen/src/visitor/call.rs
+++ b/codegen/src/visitor/call.rs
@@ -60,8 +60,6 @@ impl CodeGen {
             .get(&index)
             .ok_or(Error::ImportedFuncNotFound(index))?;
 
-        func.prelude(&mut self.masm)?;
-
         match func {
             Func::Sstore => self.masm._sstore(),
             Func::Sload => self.masm._sload(),
diff --git a/compiler/tests/storage.rs b/compiler/tests/storage.rs
index cd596f223..f73190ceb 100644
--- a/compiler/tests/storage.rs
+++ b/compiler/tests/storage.rs
@@ -45,19 +45,19 @@ fn basic() -> Result<()> {
 
 #[test]
 fn dispatcher() -> Result<()> {
-    let _bytecode = common::load_with_dispatcher("storage", "dispatcher")?;
+    let bytecode = common::load_with_dispatcher("storage", "dispatcher")?;
 
     // TODO: testing set (#122)
-    // {
-    //     let key = 0;
-    //     let value = 42;
-    //     let mut selector = zabi::selector(b"set(i32)").to_vec();
-    //     selector = [selector, 42.to_bytes32().to_vec()].concat();
-    //     let info = EVM::run(&bytecode, &selector);
-    //     assert_eq!(info.instr, InstructionResult::Return);
-    //     assert_eq!(info.ret, []);
-    //     assert_eq!(info.storage.get(&U256::from(key)), Some(&U256::from(value)));
-    // }
+    {
+        let key = 0;
+        let value = 42;
+        let mut selector = zabi::selector(b"set(i32)").to_vec();
+        selector = [selector, 42.to_bytes32().to_vec()].concat();
+        let info = EVM::run(&bytecode, &selector);
+        assert_eq!(info.instr, InstructionResult::Return);
+        assert_eq!(info.ret, []);
+        assert_eq!(info.storage.get(&U256::from(key)), Some(&U256::from(value)));
+    }
 
     // let info = EVM::run(&bytecode, &42.to_bytes32());
 
diff --git a/compiler/wat/storage/basic.wat b/compiler/wat/storage/basic.wat
index 61b9c8633..d9428db01 100644
--- a/compiler/wat/storage/basic.wat
+++ b/compiler/wat/storage/basic.wat
@@ -4,8 +4,8 @@
   (import "evm" "sstore" (func (;0;) (type 1)))
   (import "evm" "sload" (func (;1;) (type 0)))
   (func (;2;) (type 0) (param i32) (result i32)
-    i32.const 0
     local.get 0
+    i32.const 0
     call 0
     i32.const 0
     call 1))
diff --git a/compiler/wat/storage/dispatcher.wat b/compiler/wat/storage/dispatcher.wat
index 5c502a408..b5c0ce792 100644
--- a/compiler/wat/storage/dispatcher.wat
+++ b/compiler/wat/storage/dispatcher.wat
@@ -9,8 +9,8 @@
   (import "zinkc" "emit_abi" (func (;2;) (type 1)))
   (import "env" "memory" (memory (;0;) 17))
   (func (;3;) (type 2) (param i32) (result i32)
-    i32.const 0
     local.get 0
+    i32.const 0
     call 0
     i32.const 0
     call 1)
@@ -19,8 +19,8 @@
     i32.const 34
     call 2)
   (func (;5;) (type 3) (param i32)
-    i32.const 0
     local.get 0
+    i32.const 0
     call 0)
   (func (;6;) (type 0)
     i32.const 1048610
diff --git a/compiler/wat/storage/load.wat b/compiler/wat/storage/load.wat
index 88ca518e2..efcbafe07 100644
--- a/compiler/wat/storage/load.wat
+++ b/compiler/wat/storage/load.wat
@@ -4,8 +4,8 @@
   (import "evm" "sload" (func (;0;) (type 0)))
   (import "evm" "sstore" (func (;1;) (type 1)))
   (func (type 0) (param i32) (result i32)
-        i32.const 0
         local.get 0
+        i32.const 0
         call 1
         i32.const 0
         call 0))
diff --git a/compiler/wat/storage/store.wat b/compiler/wat/storage/store.wat
index b263c01bd..c17e935c1 100644
--- a/compiler/wat/storage/store.wat
+++ b/compiler/wat/storage/store.wat
@@ -2,7 +2,7 @@
   (type (;0;) (func (param i32 i32)))
   (import "evm" "sstore" (func (;0;) (type 0)))
   (func (param i32)
-        i32.const 0
         local.get 0
+        i32.const 0
         call 0)
  )
diff --git a/examples/Cargo.lock b/examples/Cargo.lock
index 4e75d5bba..0fc9552e5 100644
--- a/examples/Cargo.lock
+++ b/examples/Cargo.lock
@@ -9,21 +9,6 @@ dependencies = [
  "zink",
 ]
 
-[[package]]
-name = "atomic-polyfill"
-version = "0.1.11"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e3ff7eb3f316534d83a8a2c3d1674ace8a5a71198eba31e2e2b597833f699b28"
-dependencies = [
- "critical-section",
-]
-
-[[package]]
-name = "autocfg"
-version = "1.1.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d468802bab17cbc0cc575e9b053f41e72aa36bfa6b7f55e3529ffa43161b97fa"
-
 [[package]]
 name = "block-buffer"
 version = "0.10.4"
@@ -33,12 +18,6 @@ dependencies = [
  "generic-array",
 ]
 
-[[package]]
-name = "byteorder"
-version = "1.5.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1fd0f2584146f6f2ef48085050886acf353beff7305ebd1ae69500e27c67f64b"
-
 [[package]]
 name = "cobs"
 version = "0.2.3"
@@ -54,12 +33,6 @@ dependencies = [
  "libc",
 ]
 
-[[package]]
-name = "critical-section"
-version = "1.1.2"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7059fff8937831a9ae6f0fe4d658ffabf58f2ca96aa9dec1c889f936f705f216"
-
 [[package]]
 name = "crypto-common"
 version = "0.1.6"
@@ -103,29 +76,6 @@ dependencies = [
  "version_check",
 ]
 
-[[package]]
-name = "hash32"
-version = "0.2.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b0c35f58762feb77d74ebe43bdbc3210f09be9fe6742234d573bacc26ed92b67"
-dependencies = [
- "byteorder",
-]
-
-[[package]]
-name = "heapless"
-version = "0.7.16"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "db04bc24a18b9ea980628ecf00e6c0264f3c1426dac36c00cb49b6fbad8b0743"
-dependencies = [
- "atomic-polyfill",
- "hash32",
- "rustc_version",
- "serde",
- "spin",
- "stable_deref_trait",
-]
-
 [[package]]
 name = "hex"
 version = "0.4.3"
@@ -154,16 +104,6 @@ version = "0.2.149"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "a08173bc88b7955d1b3145aa561539096c421ac8debde8cbc3612ec635fee29b"
 
-[[package]]
-name = "lock_api"
-version = "0.4.11"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "3c168f8615b12bc01f9c17e2eb0cc07dcae1940121185446edc3744920e8ef45"
-dependencies = [
- "autocfg",
- "scopeguard",
-]
-
 [[package]]
 name = "log"
 version = "0.1.0"
@@ -179,7 +119,6 @@ checksum = "a55c51ee6c0db07e68448e336cf8ea4131a620edefebf9893e759b2d793420f8"
 dependencies = [
  "cobs",
  "embedded-io",
- "heapless",
  "serde",
 ]
 
@@ -201,27 +140,6 @@ dependencies = [
  "proc-macro2",
 ]
 
-[[package]]
-name = "rustc_version"
-version = "0.4.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "bfa0f585226d2e68097d4f95d113b15b83a82e819ab25717ec0590d9584ef366"
-dependencies = [
- "semver",
-]
-
-[[package]]
-name = "scopeguard"
-version = "1.2.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "94143f37725109f92c262ed2cf5e59bce7498c01bcc1502d7b9afe439a4e9f49"
-
-[[package]]
-name = "semver"
-version = "1.0.20"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "836fa6a3e1e547f9a2c4040802ec865b5d85f4014efe00555d7090a3dcaa1090"
-
 [[package]]
 name = "serde"
 version = "1.0.189"
@@ -252,21 +170,6 @@ dependencies = [
  "keccak",
 ]
 
-[[package]]
-name = "spin"
-version = "0.9.8"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "6980e8d7511241f8acf4aebddbb1ff938df5eebe98691418c4468d0b72a96a67"
-dependencies = [
- "lock_api",
-]
-
-[[package]]
-name = "stable_deref_trait"
-version = "1.2.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a8f112729512f8e442d81f95a8a7ddf2b7c6b8a1a6f509a95864142b30cab2d3"
-
 [[package]]
 name = "storage"
 version = "0.1.0"
diff --git a/zink/codegen/src/storage.rs b/zink/codegen/src/storage.rs
index e2b1a204c..17629612b 100644
--- a/zink/codegen/src/storage.rs
+++ b/zink/codegen/src/storage.rs
@@ -45,7 +45,7 @@ pub fn parse(input: ItemType) -> TokenStream {
 
             fn set(value: #variable_type) {
                 unsafe {
-                    zink::ffi::evm::sstore(Self::STORAGE_KEY, value);
+                    zink::ffi::evm::sstore(value, Self::STORAGE_KEY);
                 }
             }
         }
@@ -61,6 +61,6 @@ mod tests {
     #[test]
     fn parse_test() {
         let expr: ItemType = syn::parse_str("pub type Counter = i32;").unwrap();
-        assert_eq!(parse(expr).to_string().as_str(), "struct Counter ; impl zink :: Storage < i32 > for Counter { const STORAGE_KEY : i32 = 0i32 ; fn get () -> i32 { unsafe { zink :: ffi :: evm :: sload (Self :: STORAGE_KEY) } } fn set (value : i32) { unsafe { zink :: ffi :: evm :: sstore (Self :: STORAGE_KEY , value) ; } } }");
+        assert_eq!(parse(expr).to_string().as_str(), "struct Counter ; impl zink :: Storage < i32 > for Counter { const STORAGE_KEY : i32 = 0i32 ; fn get () -> i32 { unsafe { zink :: ffi :: evm :: sload (Self :: STORAGE_KEY) } } fn set (value : i32) { unsafe { zink :: ffi :: evm :: sstore (value , Self :: STORAGE_KEY) ; } } }");
     }
 }
diff --git a/zink/src/ffi/evm.rs b/zink/src/ffi/evm.rs
index fadd7582e..09af6e9ec 100644
--- a/zink/src/ffi/evm.rs
+++ b/zink/src/ffi/evm.rs
@@ -9,7 +9,7 @@ extern "C" {
     // i32 -> 8 bytes
 
     /// Store a value in the storage
-    pub fn sstore(key: i32, value: i32);
+    pub fn sstore(value: i32, key: i32);
 
     /// Load a value from the storage
     pub fn sload(key: i32) -> i32;