diff --git a/lxsession/lxsession-logout/lxsession-logout.c b/lxsession/lxsession-logout/lxsession-logout.c
index b0b817c..412244d 100644
--- a/lxsession/lxsession-logout/lxsession-logout.c
+++ b/lxsession/lxsession-logout/lxsession-logout.c
@@ -111,7 +111,10 @@ static gboolean verify_running(const char * display_manager, const char * execut
 
         /* Form the filespec of the pid file for the display manager. */
         char buffer[PATH_MAX];
-        sprintf(buffer, "/var/run/%s.pid", display_manager);
+        if (strcmp(display_manager, "kdm") != 0)
+            sprintf(buffer, "/var/run/%s.pid", display_manager);
+        else
+            sprintf(buffer, "/var/run/xdm.pid");
 
         /* Open the pid file. */
         int fd = open(buffer, O_RDONLY);