diff --git a/.github/workflows/toy.yml b/.github/workflows/toy.yml
new file mode 100644
index 0000000..257cc31
--- /dev/null
+++ b/.github/workflows/toy.yml
@@ -0,0 +1,20 @@
+name: Run the tests
+
+on:
+  push:
+    branches: [ main ]
+  pull_request:
+    branches: [ main ]
+
+env:
+  CARGO_TERM_COLOR: always
+
+jobs:
+  run_unit_tests:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Check out the repository
+        uses: actions/checkout@v2
+
+      - name: Perform the tests
+        run: cargo run --package cranelift-jit-demo --bin toy
diff --git a/Cargo.toml b/Cargo.toml
index 425921a..75058d8 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -8,7 +8,7 @@ description = "Toy language implemented using cranelift-jit"
 edition = "2018"
 
 [dependencies]
-peg = "0.6"
-cranelift = "0.85.1"
-cranelift-module = "0.85.1"
-cranelift-jit = "0.85.1"
+peg = "0.8.1"
+cranelift = "0.89.1"
+cranelift-module = "0.89.1"
+cranelift-jit = "0.89.1"
diff --git a/README.md b/README.md
index 04214f4..bd79b9a 100644
--- a/README.md
+++ b/README.md
@@ -18,12 +18,12 @@ and it makes efficient use of memory.
 And Cranelift is being architected to allow flexibility in how one uses it.
 Sometimes that flexibility can be a burden, which we've recently started to
 address in a new set of crates, `cranelift-module`, `cranelift-jit`, and
-`cranelift-faerie`, which put the pieces together in some easy-to-use
+`cranelift-object`, which put the pieces together in some easy-to-use
 configurations for working with multiple functions at once. `cranelift-module`
 is a common interface for working with multiple functions and data interfaces
 at once. This interface can sit on top of `cranelift-jit`, which writes
 code and data to memory where they can be executed and accessed. And, it can
-sit on top of `cranelift-faerie`, which writes code and data to native .o files
+sit on top of `cranelift-object`, which writes code and data to native .o files
 which can be linked into native executables.
 
 This post introduces Cranelift by walking through a JIT demo, using
diff --git a/src/bin/toy.rs b/src/bin/toy.rs
index a12bace..65724f0 100644
--- a/src/bin/toy.rs
+++ b/src/bin/toy.rs
@@ -13,6 +13,7 @@ fn main() -> Result<(), String> {
         "iterative_fib(10) = {}",
         run_iterative_fib_code(&mut jit, 10)?
     );
+    run_call_builtin_symbol(&mut jit)?;
     run_hello(&mut jit)?;
     Ok(())
 }
@@ -29,11 +30,20 @@ fn run_iterative_fib_code(jit: &mut jit::JIT, input: isize) -> Result<isize, Str
     unsafe { run_code(jit, ITERATIVE_FIB_CODE, input) }
 }
 
+fn run_call_builtin_symbol(jit: &mut jit::JIT) -> Result<isize, String> {
+    unsafe {
+        jit.create_data("example_string", *b"Example String\0")?;
+        run_code(jit, CALL_BUILTIN_SYMBOL_CODE, ())
+    }
+}
 fn run_hello(jit: &mut jit::JIT) -> Result<isize, String> {
-    jit.create_data("hello_string", "hello world!\0".as_bytes().to_vec())?;
-    unsafe { run_code(jit, HELLO_CODE, ()) }
+    unsafe {
+        jit.create_data("hello_string", *b"hello world!\0")?;
+        run_code(jit, HELLO_CODE, ())
+    }
 }
 
+
 /// Executes the given code using the cranelift JIT compiler.
 ///
 /// Feeds the given input into the JIT compiled function and returns the resulting output.
@@ -71,6 +81,7 @@ const FOO_CODE: &str = r#"
             50
         }
         c = c + 2
+        assert_int(c, 42)
     }
 "#;
 
@@ -105,9 +116,17 @@ const ITERATIVE_FIB_CODE: &str = r#"
                 n = n - 1
             }
         }
+        assert_int(r, 55)
     }
 "#;
 
+const CALL_BUILTIN_SYMBOL_CODE: &str = r#"
+fn call_builtin_symbol() -> (r) {
+    println_string(&example_string)
+    println_int(10)
+}
+"#;
+
 /// Let's say hello, by calling into libc. The puts function is resolved by
 /// dlsym to the libc function, and the string &hello_string is defined below.
 const HELLO_CODE: &str = r#"
diff --git a/src/builtins.rs b/src/builtins.rs
new file mode 100644
index 0000000..e701a39
--- /dev/null
+++ b/src/builtins.rs
@@ -0,0 +1,14 @@
+use std::ffi::{c_char, CStr};
+
+pub unsafe extern fn println_string(string: *const c_char) {
+    let cstr = CStr::from_ptr(string);
+    println!("{}", cstr.to_str().unwrap())
+}
+
+pub extern fn println_int(int: isize) {
+    println!("{}", int)
+}
+
+pub extern fn assert_int(int: isize, pre: isize) {
+    assert_eq!(int, pre)
+}
diff --git a/src/jit.rs b/src/jit.rs
index 9818a30..fa956df 100644
--- a/src/jit.rs
+++ b/src/jit.rs
@@ -3,7 +3,7 @@ use cranelift::prelude::*;
 use cranelift_jit::{JITBuilder, JITModule};
 use cranelift_module::{DataContext, Linkage, Module};
 use std::collections::HashMap;
-use std::slice;
+use crate::builtins::{assert_int, println_int, println_string};
 
 /// The basic JIT class.
 pub struct JIT {
@@ -26,8 +26,11 @@ pub struct JIT {
 
 impl Default for JIT {
     fn default() -> Self {
-        let builder = JITBuilder::new(cranelift_module::default_libcall_names());
-        let module = JITModule::new(builder.unwrap());
+        let mut builder = JITBuilder::new(cranelift_module::default_libcall_names()).unwrap();
+        builder.symbol("println_string", println_string as *const u8);
+        builder.symbol("println_int", println_int as *const u8);
+        builder.symbol("assert_int", assert_int as *const u8);
+        let module = JITModule::new(builder);
         Self {
             builder_context: FunctionBuilderContext::new(),
             ctx: module.make_context(),
@@ -84,12 +87,12 @@ impl JIT {
     }
 
     /// Create a zero-initialized data section.
-    pub fn create_data(&mut self, name: &str, contents: Vec<u8>) -> Result<&[u8], String> {
+    pub unsafe fn create_data<D>(&mut self, name: &str, data: D) -> Result<(*mut D, usize), String> {
+        // println!("CreateData: Name: {}, Type: {}", name ,std::any::type_name::<D>());
         // The steps here are analogous to `compile`, except that data is much
         // simpler than functions.
-        self.data_ctx.define(contents.into_boxed_slice());
-        let id = self
-            .module
+        self.data_ctx.define_zeroinit(std::mem::size_of::<D>());
+        let id = self.module
             .declare_data(name, Linkage::Export, true, false)
             .map_err(|e| e.to_string())?;
 
@@ -98,9 +101,12 @@ impl JIT {
             .map_err(|e| e.to_string())?;
         self.data_ctx.clear();
         self.module.finalize_definitions();
-        let buffer = self.module.get_finalized_data(id);
-        // TODO: Can we move the unsafe into cranelift?
-        Ok(unsafe { slice::from_raw_parts(buffer.0, buffer.1) })
+        let (ptr, size) = self.module.get_finalized_data(id);
+        let ptr = ptr as *const D as *mut D;
+        unsafe {
+            ptr.write(data);
+        }
+        Ok((ptr, size))
     }
 
     // Translate from toy-language AST nodes into Cranelift IR.
@@ -176,7 +182,7 @@ impl JIT {
 /// A collection of state used for translating from toy-language AST nodes
 /// into Cranelift IR.
 struct FunctionTranslator<'a> {
-    int: types::Type,
+    int: Type,
     builder: FunctionBuilder<'a>,
     variables: HashMap<String, Variable>,
     module: &'a mut JITModule,
diff --git a/src/lib.rs b/src/lib.rs
index 9af7cb3..8a78dd9 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,2 +1,3 @@
 pub mod frontend;
 pub mod jit;
+pub mod builtins;