diff --git a/src/shell-window-tracker.c b/src/shell-window-tracker.c
index 075cb2a16..99ed8270c 100644
--- a/src/shell-window-tracker.c
+++ b/src/shell-window-tracker.c
@@ -343,7 +343,7 @@ get_app_from_window_pid (ShellWindowTracker  *tracker,
 
   pid = meta_window_get_pid (window);
 
-  if (pid == -1)
+  if (pid < 1)
     return NULL;
 
   result = shell_window_tracker_get_app_from_pid (tracker, pid);