diff --git a/hive-bash-mcp/src/runner.rs b/hive-bash-mcp/src/runner.rs
index 48b15012..95bc833c 100644
--- a/hive-bash-mcp/src/runner.rs
+++ b/hive-bash-mcp/src/runner.rs
@@ -762,7 +762,15 @@ async fn exec_cmd(
     // `kill` and the timeout would have nothing left to act on.
     let stdout_file = std::fs::File::create(out_path)?;
     let stderr_file = std::fs::File::create(err_path)?;
-    let mut cmd_builder = Command::new("/usr/bin/env");
+    //
+    // Where `/usr/bin/env` does not exist (the nix build sandbox, which the
+    // tests run in, has only `/bin/sh`), `env` is looked up on PATH instead.
+    let env = if Path::new("/usr/bin/env").exists() {
+        "/usr/bin/env"
+    } else {
+        "env"
+    };
+    let mut cmd_builder = Command::new(env);
     cmd_builder
         .arg("bash")
         .arg("-c")