diff --git a/crates/flat/src/encode.rs b/crates/flat/src/encode.rs
index 9a86940f..546a251f 100644
--- a/crates/flat/src/encode.rs
+++ b/crates/flat/src/encode.rs
@@ -20,6 +20,14 @@ impl Encode for u8 {
     }
 }
 
+impl Encode for isize {
+    fn encode(&self, e: &mut Encoder) -> Result<(), String> {
+        e.integer(*self)?;
+
+        Ok(())
+    }
+}
+
 impl Encode for char {
     fn encode(&self, e: &mut Encoder) -> Result<(), String> {
         e.char(*self)?;
diff --git a/crates/flat/src/encoder.rs b/crates/flat/src/encoder.rs
index 84f094c0..2bf0efa7 100644
--- a/crates/flat/src/encoder.rs
+++ b/crates/flat/src/encoder.rs
@@ -51,7 +51,13 @@ impl Encoder {
         self
     }
 
-    pub fn bytes(&mut self, arr: &[u8]) -> Result<&mut Self, String> {
+    pub fn bytes(&mut self, x: &[u8]) -> Result<&mut Self, String> {
+        // use filler to write current buffer so bits used gets reset
+        self.filler();
+        self.byte_array(x)
+    }
+
+    pub fn byte_array(&mut self, arr: &[u8]) -> Result<&mut Self, String> {
         if self.used_bits != 0 {
             return Err("Buffer is not byte aligned".to_string());
         }
@@ -59,8 +65,13 @@ impl Encoder {
         Ok(self)
     }
 
+    pub fn integer(&mut self, i: isize) -> Result<&mut Self, String> {
+        self.word(i);
+        Ok(self)
+    }
+
     pub fn char(&mut self, c: char) -> Result<&mut Self, String> {
-        self.word(c as u32);
+        self.word(c as isize);
         Ok(self)
     }
 
@@ -121,7 +132,7 @@ impl Encoder {
         self.write_blk(arr, src_ptr);
     }
 
-    fn word(&mut self, c: u32) {
+    fn word(&mut self, c: isize) {
         loop {
             let mut w = (c & 127) as u8;
             let c = c >> 7;
diff --git a/crates/uplc/src/ast.rs b/crates/uplc/src/ast.rs
index 5dc99bbc..69f61970 100644
--- a/crates/uplc/src/ast.rs
+++ b/crates/uplc/src/ast.rs
@@ -74,7 +74,7 @@ pub fn safe_encode_bits(num_bits: u32, byte: u8, e: &mut Encoder) -> Result<(),
 pub enum Constant {
     // TODO: figure out the right size for this
     // tag: 0
-    Integer(i64),
+    Integer(isize),
     // tag: 1
     ByteString(Vec<u8>),
     // tag: 2
@@ -159,7 +159,10 @@ impl Encode for Term {
 impl Encode for &Constant {
     fn encode(&self, e: &mut Encoder) -> Result<(), String> {
         match self {
-            Constant::Integer(_) => todo!(),
+            Constant::Integer(i) => {
+                encode_constant(0, e)?;
+                i.encode(e)?;
+            }
             Constant::ByteString(bytes) => {
                 encode_constant(1, e)?;
                 bytes.encode(e)?;