diff --git a/src/newgrf_debug_gui.cpp b/src/newgrf_debug_gui.cpp
--- a/src/newgrf_debug_gui.cpp
+++ b/src/newgrf_debug_gui.cpp
@@ -519,7 +519,7 @@ static const NWidgetPart _nested_newgrf_
 };
 
 static WindowDesc _newgrf_inspect_desc(
-	WDP_AUTO, 400, 300,
+	WDP_AUTO, "newgrf_inspect", 400, 300,
 	WC_NEWGRF_INSPECT, WC_NONE,
 	0,
 	_nested_newgrf_inspect_widgets, lengthof(_nested_newgrf_inspect_widgets)
@@ -873,7 +873,7 @@ static const NWidgetPart _nested_sprite_
 };
 
 static WindowDesc _sprite_aligner_desc(
-	WDP_AUTO, 400, 300,
+	WDP_AUTO, "sprite_aligner", 400, 300,
 	WC_SPRITE_ALIGNER, WC_NONE,
 	0,
 	_nested_sprite_aligner_widgets, lengthof(_nested_sprite_aligner_widgets)