diff --git a/crates/flat/src/decode.rs b/crates/flat/src/decode.rs
index 7bd7c7f4..a9affaef 100644
--- a/crates/flat/src/decode.rs
+++ b/crates/flat/src/decode.rs
@@ -1,5 +1,11 @@
-use crate::decoder::Decoder;
+use crate::{decoder::Decoder, filler::Filler};
 
 pub trait Decode<'b>: Sized {
     fn decode(d: &mut Decoder<'b>) -> Result<Self, String>;
 }
+
+impl<'b> Decode<'b> for Filler {
+    fn decode(d: &mut Decoder<'b>) -> Result<Self, String> {
+        todo!()
+    }
+}
diff --git a/crates/flat/src/decoder.rs b/crates/flat/src/decoder.rs
index 21f41fec..6923528d 100644
--- a/crates/flat/src/decoder.rs
+++ b/crates/flat/src/decoder.rs
@@ -2,6 +2,7 @@ use crate::decode::Decode;
 
 pub struct Decoder<'b> {
     buffer: &'b [u8],
+    used_bits: i64,
     pos: usize,
 }
 
@@ -10,6 +11,7 @@ impl<'b> Decoder<'b> {
         Decoder {
             buffer: bytes,
             pos: 0,
+            used_bits: 0,
         }
     }
 
diff --git a/crates/flat/src/lib.rs b/crates/flat/src/lib.rs
index eb0769cd..8a11995b 100644
--- a/crates/flat/src/lib.rs
+++ b/crates/flat/src/lib.rs
@@ -43,7 +43,11 @@ where
 {
     let mut d = de::Decoder::new(bytes);
 
-    d.decode()
+    let value = d.decode()?;
+
+    d.decode::<filler::Filler>()?;
+
+    Ok(value)
 }
 
 #[cfg(test)]