diff --git a/env.scm b/env.scm
index e9bc003..f6ad7e5 100644
--- a/env.scm
+++ b/env.scm
@@ -39,7 +39,7 @@
             remove-env-no-checks!
             roll-back!
             environment->overlay-mount-maybe
-            unmount-environment
+            unmount-environment-maybe
             environment-mounted?))
 
 (define directory-files (@@ (ice-9 ftw) directory-files))
@@ -431,15 +431,18 @@ by other environments made."
           (0 (values (make-overlay-mount layers-links upper work merged) 0))
           (err (values #f err)))))))
 
-(define (unmount-environment env)
+(define (unmount-environment-maybe env)
   (let* ((name (symbol->string (environment-name env)))
          (dir (string-append %env-directory "/" name))
          (tmpdirln (string-append "/tmp/genv/" name)))
-    (when (file-exists? dir)
-      (system* "umount" dir)
-      (delete-file-recursively dir))
-    (when (file-exists? tmpdirln)
-      (delete-file tmpdirln))))
+    (if (file-exists? (string-append tmpdirln "/lock"))
+        #f
+        (begin
+          (when (file-exists? dir)
+            (system* "umount" dir)
+            (delete-file-recursively dir))
+          (when (file-exists? tmpdirln)
+            (delete-file tmpdirln))))))
 
 (define (fuse-overlayfs-mounts)
   (filter (λ (m) (equal? "fuse.fuse-overlayfs"