diff --git a/Outputs/CRT/CRT.cpp b/Outputs/CRT/CRT.cpp
index d5c99866c..55157b83c 100644
--- a/Outputs/CRT/CRT.cpp
+++ b/Outputs/CRT/CRT.cpp
@@ -362,6 +362,7 @@ Outputs::CRT::Rect CRT::get_rect_for_area(int first_line_after_sync, int number_
 {
 	first_cycle_after_sync *= _time_multiplier;
 	number_of_cycles *= _time_multiplier;
+	number_of_lines++;
 
 	// determine prima facie x extent
 	unsigned int horizontal_period = _horizontal_flywheel->get_standard_period();