diff --git a/nix/microvm/user-config.nix b/nix/microvm/user-config.nix
index c7ba38e5..1168af25 100644
--- a/nix/microvm/user-config.nix
+++ b/nix/microvm/user-config.nix
@@ -115,7 +115,8 @@ in {
   # put the devshell into the resulting image env.
   # we do this instead of using a `.nix` file because it lets us skip eval time.
   environment.etc = lib.mkIf (dependencies != []) {
-    "spindle/devshell.drv".source = spindleDevShell.drvPath;
+    # this is safe because we have the closure in the env also!
+    "spindle/devshell-drv".text = builtins.unsafeDiscardStringContext spindleDevShell.drvPath;
     "spindle/devshell-closure".source = pkgs.closureInfo {rootPaths = [spindleDevShell];};
   };
   services = builtins.mapAttrs (normalize (options.services or {})) (userConfig.services or {});
diff --git a/shuttle/src/activation.rs b/shuttle/src/activation.rs
index 79af5b23..d5ae31b2 100644
--- a/shuttle/src/activation.rs
+++ b/shuttle/src/activation.rs
@@ -10,7 +10,7 @@ use tracing::info;
 
 const USER_CONFIG_DIR: &str = "/run/spindle/user-config";
 const DEVSHELL_ENV_PATH: &str = "/run/spindle/devshell-env.sh";
-const DEVSHELL_DRV: &str = "/etc/spindle/devshell.drv";
+const DEVSHELL_DRV: &str = "/etc/spindle/devshell-drv";
 
 pub async fn run(id: String, req: v1::ActivateConfig, out: Sender<Message>) {
     let config_key = req.config_key.clone();
@@ -58,13 +58,15 @@ async fn activate(id: &str, req: &v1::ActivateConfig, out: &Sender<Message>) ->
 }
 
 async fn write_devshell_env(timeout: Duration) -> Result<()> {
-    let drv = match fs::canonicalize(DEVSHELL_DRV) {
-        Ok(p) => p,
-        Err(_) => {
-            let _ = fs::remove_file(DEVSHELL_ENV_PATH);
-            return Ok(());
-        }
-    };
+    let pointer = Path::new(DEVSHELL_DRV);
+    if !pointer.exists() {
+        let _ = fs::remove_file(DEVSHELL_ENV_PATH);
+        return Ok(());
+    }
+    let drv = fs::read_to_string(&pointer)
+        .with_context(|| format!("read {pointer:?}"))?
+        .trim()
+        .to_owned();
 
     info!(
         ?drv,
@@ -72,11 +74,7 @@ async fn write_devshell_env(timeout: Duration) -> Result<()> {
     );
     let output = run_capture(
         Spec::new(nix_executable())
-            .args([
-                "print-dev-env".into(),
-                "--show-trace".into(),
-                drv.into_os_string(),
-            ])
+            .args(["print-dev-env", "--show-trace", &drv])
             .cwd(SPINDLE_RUN_DIR)
             .timeout(timeout),
     )
diff --git a/spindle/engines/microvm/test-spindle-microvm.sh b/spindle/engines/microvm/test-spindle-microvm.sh
index 9eac70cf..142cf55c 100755
--- a/spindle/engines/microvm/test-spindle-microvm.sh
+++ b/spindle/engines/microvm/test-spindle-microvm.sh
@@ -338,7 +338,7 @@ run_vm() {
         --work-dir "$work_dir"
         --exec-timeout "$timeout"
         --port "${SPINDLE_TEST_VSOCK_PORT:-10240}"
-        --memory-mib 2049
+        --memory-mib 4096
     )
 
     if [ "$no_cache" -eq 0 ]; then