diff --git a/src/interpret.rs b/src/interpret.rs
index 5775f73..eb6bb2e 100644
--- a/src/interpret.rs
+++ b/src/interpret.rs
@@ -208,16 +208,26 @@ impl ExecEnv {
                 args: _,
                 body: _,
             } => todo!(),
-            StmtKind::BfFunctio { .. } => todo!(),
-            // This is missing from StmtKind after the interpreter
-            // rewrite; presumably, parsing is not yet implemented for
-            // it. ~~Alex
-            // StmtKind::BfFDeclaration { iden, body } => {
-            //     self.decl_var(
-            //         &iden.0,
-            //         Value::Functio(Functio::BfFunctio(body.as_bytes().into())),
-            //     );
-            // }
+            StmtKind::BfFunctio {
+                iden,
+                tape_len,
+                code,
+            } => {
+                self.decl_var(
+                    &iden.iden,
+                    Value::Functio(Functio::BfFunctio {
+                        instructions: code.to_owned(),
+                        tape_len: tape_len
+                            .as_ref()
+                            .map(|tape_len| {
+                                self.eval_expr(tape_len)
+                                    .and_then(|v| v.to_i32(&stmt.span))
+                                    .map(|len| len as usize)
+                            })
+                            .unwrap_or(Ok(crate::brian::DEFAULT_TAPE_SIZE_LIMIT))?,
+                    }),
+                );
+            }
             StmtKind::If { cond, body } => {
                 if self.eval_expr(cond)?.to_bool() {
                     return self.eval_stmts_hs(&body.block, true);
@@ -228,7 +238,10 @@ impl ExecEnv {
                 match func {
                     Value::Functio(func) => {
                         match func {
-                            Functio::BfFunctio(body) => {
+                            Functio::BfFunctio {
+                                instructions,
+                                tape_len,
+                            } => {
                                 let mut input: Vec<u8> = vec![];
                                 for arg in args {
                                     self.eval_expr(arg)?.bf_write(&mut input);
@@ -236,11 +249,16 @@ impl ExecEnv {
                                 println!("input = {:?}", input);
                                 let mut output = vec![];
 
-                                crate::brian::interpret_with_io(&body, &input as &[_], &mut output)
-                                    .map_err(|e| Error {
-                                        kind: ErrorKind::BfInterpretError(e),
-                                        span: stmt.span.clone(),
-                                    })?;
+                                crate::brian::Interpreter::from_ascii_with_tape_limit(
+                                    &instructions,
+                                    &input as &[_],
+                                    tape_len,
+                                )
+                                .interpret_with_output(&mut output)
+                                .map_err(|e| Error {
+                                    kind: ErrorKind::BfInterpretError(e),
+                                    span: stmt.span.clone(),
+                                })?;
 
                                 // I guess Brainfuck functions write
                                 // output to stdout? It's not quite
diff --git a/src/variables.rs b/src/variables.rs
index fe8d358..978635c 100644
--- a/src/variables.rs
+++ b/src/variables.rs
@@ -36,7 +36,10 @@ impl From<Abool> for bool {
 
 #[derive(Debug, PartialEq, Clone)]
 pub enum Functio {
-    BfFunctio(Vec<u8>),
+    BfFunctio {
+        instructions: Vec<u8>,
+        tape_len: usize,
+    },
     AbleFunctio(Vec<Stmt>),
 }
 
@@ -94,10 +97,17 @@ impl Value {
                 }])
             }),
             Value::Functio(f) => stream.write_all(&[5]).and_then(|_| match f {
-                Functio::BfFunctio(f) => stream
-                    .write_all(&[0])
-                    .and_then(|_| stream.write_all(&(f.len() as u32).to_le_bytes()))
-                    .and_then(|_| stream.write_all(&f)),
+                Functio::BfFunctio {
+                    instructions,
+                    tape_len: _,
+                } => {
+                    // NOTE(Alex): Tape length should maybe be taken
+                    // into account here.
+                    stream
+                        .write_all(&[0])
+                        .and_then(|_| stream.write_all(&(instructions.len() as u32).to_le_bytes()))
+                        .and_then(|_| stream.write_all(&instructions))
+                }
                 Functio::AbleFunctio(_) => {
                     todo!()
                 }
@@ -148,11 +158,12 @@ impl Display for Value {
             Value::Bool(v) => write!(f, "{}", v),
             Value::Abool(v) => write!(f, "{}", v),
             Value::Functio(v) => match v {
-                Functio::BfFunctio(source) => {
+                Functio::BfFunctio { instructions, tape_len } => {
                     write!(
                         f,
-                        "{}",
-                        String::from_utf8(source.to_owned())
+                        "({}) {}",
+                        tape_len,
+                        String::from_utf8(instructions.to_owned())
                             .expect("Brainfuck functio source should be UTF-8")
                     )
                 }