diff --git a/src/builtins/mod.rs b/src/builtins/mod.rs
index ac07bb9..c851029 100644
--- a/src/builtins/mod.rs
+++ b/src/builtins/mod.rs
@@ -38,4 +38,9 @@ mod tests {
     fn test_is_builtin_cd() {
         assert_eq!(is_builtin("cd"), true);
     }
+
+    #[test]
+    fn test_is_builtin_notabuiltin() {
+        assert_eq!(is_builtin("notabuiltin"), false)
+    }
 }