diff --git a/README.md b/README.md
index 158feaa..254d94c 100644
--- a/README.md
+++ b/README.md
@@ -53,7 +53,7 @@ implemented.
     statement, functions
   - 🌕 stage 1: lazy evaluation
   - 🌘 stage 2:
-    - 🌘 built-in functions (progress: 2 out of 111)
+    - 🌘 built-in functions (progress: 3 out of 111)
     - 🌑 derivations (hello world derivation)
   - 🌑 stage 3: full implementation (all derivations in nixpkgs, nice error
     messages, etc.)
diff --git a/flake.lock b/flake.lock
index fd56624..07f12ba 100644
--- a/flake.lock
+++ b/flake.lock
@@ -2,11 +2,11 @@
   "nodes": {
     "nixpkgs": {
       "locked": {
-        "lastModified": 1689413807,
-        "narHash": "sha256-exuzOvOhGAEKWQKwDuZAL4N8a1I837hH5eocaTcIbLc=",
+        "lastModified": 1689631193,
+        "narHash": "sha256-AGSkBZaiTODQc8eT1rZDrQIjtb8JtFwJ0wVPzArlrnM=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "46ed466081b9cad1125b11f11a2af5cc40b942c7",
+        "rev": "57695599bdc4f7bfe5d28cfa23f14b3d8bdf8a5f",
         "type": "github"
       },
       "original": {
@@ -35,11 +35,11 @@
         "nixpkgs": "nixpkgs_2"
       },
       "locked": {
-        "lastModified": 1689497845,
-        "narHash": "sha256-DASATRkvF6Mvkq92q6ntRqQgxNV69qtJZAIJP6nlomc=",
+        "lastModified": 1689706907,
+        "narHash": "sha256-A+jUzcZraJYQ9YyfOmKub1ItPl5r/fzlkWr5gNTUOeg=",
         "owner": "urbas",
         "repo": "nixrt",
-        "rev": "0038327e3b16afced4e781570dd27eec72b605df",
+        "rev": "304a8c13e4b7b8082692ef93a19b92da677908eb",
         "type": "github"
       },
       "original": {
diff --git a/rust-toolchain.toml b/rust-toolchain.toml
index 7de68d0..338c5de 100644
--- a/rust-toolchain.toml
+++ b/rust-toolchain.toml
@@ -1,4 +1,4 @@
 [toolchain]
-channel = "1.70.0"
+channel = "1.71.0"
 components = [ "clippy", "rust-analyzer", "rustfmt" ]
 profile = "minimal"
\ No newline at end of file
diff --git a/src/eval/nix_v8.rs b/src/eval/nix_v8.rs
index 4c343db..9f68160 100644
--- a/src/eval/nix_v8.rs
+++ b/src/eval/nix_v8.rs
@@ -1227,18 +1227,13 @@ mod tests {
         assert_eq!(eval_ok(r#"rec { a = "b"; ${a} = 1; }.b"#), Value::Int(1));
     }
 
-    #[test]
-    fn test_eval_builtin_head() {
-        assert_eq!(eval_ok("builtins.head [ 1 2 ]"), Value::Int(1));
-    }
-
     #[test]
     fn test_eval_lists_are_lazy() {
         assert_eq!(eval_ok("builtins.head [ 1 (1 / 0) ]"), Value::Int(1));
     }
 
     #[test]
-    fn test_eval_abort() {
+    fn test_eval_builtin_abort() {
         let error_msg = evaluate(r#"abort "foo""#).unwrap_err();
         let expected_msg = "Evaluation aborted with the following error message: 'foo'";
         assert!(
@@ -1246,4 +1241,14 @@ mod tests {
             "Error message '{error_msg}' didn't contain '{expected_msg}'."
         );
     }
+
+    #[test]
+    fn test_eval_builtin_add() {
+        assert_eq!(eval_ok("builtins.add 1 2"), Value::Int(3));
+    }
+
+    #[test]
+    fn test_eval_builtin_head() {
+        assert_eq!(eval_ok("builtins.head [ 1 2 ]"), Value::Int(1));
+    }
 }