diff --git a/sway/config b/sway/config
index 05f8d1f..7f0fab9 100644
--- a/sway/config
+++ b/sway/config
@@ -45,6 +45,11 @@ exec feedreader --headless
 # mute microfone
 exec amixer set Capture nocap
 
+# prevent locking when fullscreen
+for_window [app_id="firefox"] inhibit_idle fullscreen
+for_window [title="VLC media player"] inhibit_idle fullscreen
+for_window [app_id="evince"] inhibit_idle fullscreen
+
 # font
 font pango:Fira Sans Mono 12