diff --git a/env/rust.scm b/env/rust.scm
index 73dd134..f6b55f2 100644
--- a/env/rust.scm
+++ b/env/rust.scm
@@ -28,6 +28,8 @@
             init-rustup-environment
             launch-rust-analyzer))
 
+(define directory-files (@@ (ice-9 ftw) directory-files))
+
 (define rustup-origin
   (let ((name "rustup")
         (commit "737ad82333742dfd350a733c1649ce4e36109773")
@@ -154,9 +156,15 @@ function."
 (define* (launch-rustup-environment #:optional home)
   (exec-in-rustup-environment '("/bin/sh") #:home home))
 
-(define* (launch-rust-analyzer env target-name
+(define* (launch-rust-analyzer env target-sym
                                #:key
-                               (tag 'current) (share '()) (expose '()))
+                               (onto (if (member target-sym
+                                                 (environment-tags env))
+                                         target-sym
+                                         'current))
+                               (share '())
+                               (expose '()))
+  (define controlled-files '(".cargo" ".rustup" ".profile"))
   (define (remap w)
     (let ((home (getenv "HOME")))
       (λ (m)
@@ -170,13 +178,11 @@ function."
                        (loop (list s s)))
                    (throw 'file-doesnt-exist))))))))
 
-  (let* ((target (string-append (@@ (env) %env-directory) "/" target-name))
+  (let* ((target (string-append (@@ (env) %env-directory)
+                                "/" (symbol->string target-sym)))
          ;; TODO should actually detect if overlay is mounted not that the
          ;; directory exists.
-         (mnt (if (file-exists? target)
-                  target
-                  (overlay-mount-merged
-                   (mount-environment env #:tag tag #:target target))))
+         (mnt (mount-environment env #:tag onto #:target target))
          (mappings (append (map (remap #f) expose)
                            (map (remap #t) share))))
     (exec-in-rustup-environment '("./.cargo/bin/rust-analyzer")
@@ -184,6 +190,23 @@ function."
                                 #:mappings mappings)
     (sync)
     (system* "umount" target)
+    (with-directory-excursion (overlay-mount-upper mnt)
+      (for-each (λ (f)
+                  (unless (member f controlled-files)
+                    (format (current-output-port)
+                            "Deleting uncontrolled-file: ~a\n"
+                            f)
+                    (delete-file-recursively f)))
+                (directory-files ".")))
+    (if (nil? (directory-files (overlay-mount-upper mnt)))
+        (display "No files to add\n")
+        (begin
+          (display "Adding layer\n")
+          (apply add-layer
+                 (list env
+                       (overlay-mount-upper mnt)
+                       onto
+                       target-sym))))
     (for-each delete-file-recursively
               (list target
                     (overlay-mount-upper mnt)