diff --git a/abi/src/codec.rs b/abi/src/codec.rs
new file mode 100644
index 000000000..041793da8
--- /dev/null
+++ b/abi/src/codec.rs
@@ -0,0 +1,46 @@
+//! Serialization and Deserialization for Zink ABI.
+
+use crate::{Abi, Error, Result};
+
+/// Implement encoding and decoding for Zink ABI.
+macro_rules! impl_codec {
+    ($ty:ident) => {
+        impl $ty {
+            /// Convert self to bytes.
+            pub fn to_bytes(&self) -> Result<Vec<u8>> {
+                postcard::to_stdvec(self).map_err(Into::into)
+            }
+
+            /// Convert self to hex string.
+            pub fn to_hex(&self) -> Result<String> {
+                Ok(hex::encode(self.to_bytes()?))
+            }
+
+            /// Convert bytes to self.
+            pub fn from_bytes(bytes: impl AsRef<[u8]>) -> Result<Self> {
+                postcard::from_bytes(bytes.as_ref()).map_err(Into::into)
+            }
+
+            /// Convert hex string to self.
+            pub fn from_hex(hex: impl AsRef<str>) -> Result<Self> {
+                Self::from_bytes(&hex::decode(hex.as_ref().trim_start_matches("0x"))?)
+            }
+        }
+
+        impl ToString for $ty {
+            fn to_string(&self) -> String {
+                self.to_hex().unwrap_or_default()
+            }
+        }
+
+        impl core::str::FromStr for $ty {
+            type Err = Error;
+
+            fn from_str(hex: &str) -> Result<Self> {
+                Self::from_hex(hex)
+            }
+        }
+    };
+}
+
+impl_codec!(Abi);
diff --git a/abi/src/lib.rs b/abi/src/lib.rs
index bbbc48521..4c7443dee 100644
--- a/abi/src/lib.rs
+++ b/abi/src/lib.rs
@@ -1,24 +1,10 @@
 //! Utils for generating of zink ABI
 pub use self::result::{Error, Result};
 use serde::{Deserialize, Serialize};
-use sha3::{Digest, Keccak256};
 
+mod codec;
 mod result;
-
-/// Generate a keccak hash of the input (sha3)
-pub fn keccak256(input: &[u8]) -> [u8; 32] {
-    let mut hasher = Keccak256::new();
-    hasher.update(input);
-    hasher.finalize().into()
-}
-
-/// Get function selector from function signature.
-pub fn selector(input: &[u8]) -> [u8; 4] {
-    let mut selector = [0u8; 4];
-    selector.copy_from_slice(&keccak256(input)[..4]);
-
-    selector
-}
+pub mod util;
 
 /// Function ABI.
 #[derive(Debug, Clone, Serialize, Deserialize)]
@@ -38,34 +24,6 @@ impl Abi {
     /// Get function selector.
     pub fn selector(&self) -> [u8; 4] {
         let sig = self.signature();
-        let mut selector = [0u8; 4];
-        selector.copy_from_slice(&keccak256(sig.as_bytes())[..4]);
-
-        selector
-    }
-
-    /// Parse ABI from bytes.
-    pub fn from_bytes(bytes: &[u8]) -> Result<Self> {
-        postcard::from_bytes(bytes).map_err(Into::into)
-    }
-
-    /// Decode ABI form hex string.
-    pub fn from_hex(hex: &str) -> Result<Self> {
-        Self::from_bytes(&hex::decode(hex)?)
-    }
-
-    /// Decode ABI form hex string.
-    pub fn from_hex_bytes(bytes: &[u8]) -> Result<Self> {
-        Self::from_hex(&String::from_utf8_lossy(bytes))
-    }
-
-    /// Convert ABI to hex string.
-    pub fn to_hex(&self) -> Result<String> {
-        self.to_bytes().map(hex::encode)
-    }
-
-    /// Convert ABI to bytes.
-    pub fn to_bytes(&self) -> Result<Vec<u8>> {
-        postcard::to_stdvec(&self).map_err(Into::into)
+        util::selector(&sig.as_bytes())
     }
 }
diff --git a/abi/src/util.rs b/abi/src/util.rs
new file mode 100644
index 000000000..4f35a4293
--- /dev/null
+++ b/abi/src/util.rs
@@ -0,0 +1,17 @@
+//! Zink ABI utils
+use sha3::{Digest, Keccak256};
+
+/// Generate a keccak hash of the input (sha3)
+pub fn keccak256(input: &[u8]) -> [u8; 32] {
+    let mut hasher = Keccak256::new();
+    hasher.update(input);
+    hasher.finalize().into()
+}
+
+/// Get function selector from function signature.
+pub fn selector(input: &[u8]) -> [u8; 4] {
+    let mut selector = [0u8; 4];
+    selector.copy_from_slice(&keccak256(input)[..4]);
+
+    selector
+}
diff --git a/codegen/src/dispatcher.rs b/codegen/src/dispatcher.rs
index 4d9a24331..decae0696 100644
--- a/codegen/src/dispatcher.rs
+++ b/codegen/src/dispatcher.rs
@@ -88,7 +88,8 @@ impl<'d> Dispatcher<'d> {
             return Err(Error::FuncNotImported("emit_abi".into()));
         }
 
-        Abi::from_hex_bytes(&self.data.load(offset, length as usize)?).map_err(Into::into)
+        let abi = self.data.load(offset, length as usize)?;
+        Abi::from_hex(String::from_utf8_lossy(&abi)).map_err(Into::into)
     }
 
     /// Emit return of ext function.
diff --git a/zint/src/contract.rs b/zint/src/contract.rs
index 7ce04c5fe..2269a39d5 100644
--- a/zint/src/contract.rs
+++ b/zint/src/contract.rs
@@ -148,7 +148,7 @@ impl Contract {
                 return Err(anyhow!("no selector provided"));
             }
 
-            calldata.extend_from_slice(&zabi::selector(&inputs[0].to_vec()));
+            calldata.extend_from_slice(&zabi::util::selector(&inputs[0].to_vec()));
             inputs = &inputs[1..];
         }