diff --git a/simulators/bochs/iodev/vga.cc b/simulators/bochs/iodev/vga.cc
index d3d0e0ac..446613c6 100644
--- a/simulators/bochs/iodev/vga.cc
+++ b/simulators/bochs/iodev/vga.cc
@@ -558,7 +558,7 @@ void bx_vga_c::determine_screen_dimensions(unsigned *piHeight, unsigned *piWidth
 {
   int ai[0x20];
   int i,h,v;
-  for (i = 0 ; i < 0x20 ; i++)
+  for (i = 0 ; i < 0x19 ; i++)
    ai[i] = BX_VGA_THIS s.CRTC.reg[i];
 
   h = (ai[1] + 1) * 8;