diff --git a/Cargo.lock b/Cargo.lock
index 104af91..8769182 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -5,3 +5,10 @@ version = 4
 [[package]]
 name = "decodal"
 version = "0.1.0"
+dependencies = [
+ "decodal-core",
+]
+
+[[package]]
+name = "decodal-core"
+version = "0.1.0"
diff --git a/Cargo.toml b/Cargo.toml
index 3c61fb9..b6620cc 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,6 +1,13 @@
-[package]
-name = "decodal"
-version = "0.1.0"
-edition = "2024"
+[workspace]
+members = [
+  "crates/decodal-core",
+  "crates/decodal-cli",
+]
+resolver = "3"
 
-[dependencies]
+[profile.release]
+opt-level = "z"
+lto = true
+codegen-units = 1
+strip = true
+panic = "abort"
diff --git a/crates/decodal-cli/Cargo.toml b/crates/decodal-cli/Cargo.toml
new file mode 100644
index 0000000..faee5fb
--- /dev/null
+++ b/crates/decodal-cli/Cargo.toml
@@ -0,0 +1,7 @@
+[package]
+name = "decodal"
+version = "0.1.0"
+edition = "2024"
+
+[dependencies]
+decodal-core = { path = "../decodal-core" }
diff --git a/crates/decodal-cli/src/main.rs b/crates/decodal-cli/src/main.rs
new file mode 100644
index 0000000..31e1e0e
--- /dev/null
+++ b/crates/decodal-cli/src/main.rs
@@ -0,0 +1,3 @@
+fn main() {
+    println!("Decodal {}", decodal_core::version());
+}
diff --git a/crates/decodal-core/Cargo.toml b/crates/decodal-core/Cargo.toml
new file mode 100644
index 0000000..da71e4d
--- /dev/null
+++ b/crates/decodal-core/Cargo.toml
@@ -0,0 +1,11 @@
+[package]
+name = "decodal-core"
+version = "0.1.0"
+edition = "2024"
+
+[features]
+default = ["std"]
+std = []
+regex = []
+
+[dependencies]
diff --git a/crates/decodal-core/src/lib.rs b/crates/decodal-core/src/lib.rs
new file mode 100644
index 0000000..bf479d9
--- /dev/null
+++ b/crates/decodal-core/src/lib.rs
@@ -0,0 +1,7 @@
+#![cfg_attr(not(feature = "std"), no_std)]
+
+extern crate alloc;
+
+pub fn version() -> &'static str {
+    env!("CARGO_PKG_VERSION")
+}
diff --git a/package.nix b/package.nix
index 560f815..0ddc6b6 100644
--- a/package.nix
+++ b/package.nix
@@ -35,6 +35,11 @@ rustPlatform.buildRustPackage {
 
   strictDeps = true;
 
+  cargoBuildFlags = [
+    "-p"
+    "decodal"
+  ];
+
   doInstallCheck = true;
   installCheckPhase = ''
     runHook preInstallCheck
diff --git a/src/main.rs b/src/main.rs
deleted file mode 100644
index e7a11a9..0000000
--- a/src/main.rs
+++ /dev/null
@@ -1,3 +0,0 @@
-fn main() {
-    println!("Hello, world!");
-}