diff --git a/exwm.el b/exwm.el
index 8e94a80..a0731d9 100644
--- a/exwm.el
+++ b/exwm.el
@@ -1002,6 +1002,7 @@ FRAME, if given, indicates the X display EXWM should manage."
     (xcb:disconnect exwm--connection))
   (setq exwm--connection nil)
   (setq exwm--terminal nil)
+  (setenv "INSIDE_EXWM" nil)
   (exwm--log "Exited"))
 
 ;;;###autoload
@@ -1025,6 +1026,7 @@ Optional argument UNDO may be either of the following symbols:
      (setq frame-resize-pixelwise t     ;mandatory; before init
            window-resize-pixelwise t
            x-no-window-manager t)
+     (setenv "INSIDE_EXWM" "1")
      ;; Ignore unrecognized command line arguments.  This can be helpful
      ;; when EXWM is launched by some session manager.
      (push #'vector command-line-functions)