diff --git a/src/textfile_gui.cpp b/src/textfile_gui.cpp
index 05c534c59b..95f2b0d773 100644
--- a/src/textfile_gui.cpp
+++ b/src/textfile_gui.cpp
@@ -134,7 +134,7 @@ void TextfileWindow::SetupScrollbars()
 	const int bottom = r.bottom - WD_FRAMETEXT_BOTTOM;
 
 	DrawPixelInfo new_dpi;
-	if (!FillDrawPixelInfo(&new_dpi, x, y, right - x + 1, r.bottom - y + 1)) return;
+	if (!FillDrawPixelInfo(&new_dpi, x, y, right - x + 1, bottom - y + 1)) return;
 	DrawPixelInfo *old_dpi = _cur_dpi;
 	_cur_dpi = &new_dpi;