diff --git a/src/lib.rs b/src/lib.rs
index 8a97753..9e8dda4 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -46,26 +46,36 @@ fn unsafe_alloc_buffer(len: usize) -> Vec<u8> {
 
 #[derive(Copy, Clone)]
 pub struct Uint160 {
-    bytes: [u8; 20],
+    pub bytes: [u8; 20],
 }
 
 #[derive(Copy, Clone)]
 pub struct Uint256 {
-    bytes: [u8; 32],
+    pub bytes: [u8; 32],
 }
 
 #[derive(Copy, Clone)]
 pub struct Uint128 {
-    bytes: [u8; 16],
+    pub bytes: [u8; 16],
 }
 
+type Address = Uint160;
+type Hash = Uint256;
+type Value = Uint128;
+
 trait EwasmType {
     fn new() -> Self;
 }
 
-type Address = Uint160;
-type Hash = Uint256;
-type Value = Uint128;
+trait RawPtr {
+    fn as_raw_ptr(&self) -> *const Self;
+}
+
+impl<T> RawPtr for T {
+    fn as_raw_ptr(&self) -> *const T {
+        self as *const T
+    }
+}
 
 impl EwasmType for Address {
     fn new() -> Self {
@@ -115,20 +125,20 @@ pub fn gas_left() -> u64 {
     }
 }
 
-pub fn current_address() -> [u8;20] {
-    let mut ret = [0u8;20];
+pub fn current_address() -> Address {
+    let mut ret = Address::new();
 
     unsafe {
-        ethereum_getAddress(ret.as_mut_ptr() as *const u32);
+        ethereum_getAddress(ret.as_raw_ptr() as *const u32);
     }
     ret
 }
 
-pub fn external_balance(address: &[u8;20]) -> [u8;16] {
-    let mut ret = [0u8;16];
+pub fn external_balance(address: Address) -> Value {
+    let mut ret = Value::new();
 
     unsafe {
-        ethereum_getBalance(address.as_ptr() as *const u32, ret.as_mut_ptr() as *const u32);
+        ethereum_getBalance(address.as_raw_ptr() as *const u32, ret.as_raw_ptr() as *const u32);
     }
     ret
 }