diff --git a/cores/c16/c16_mist.v b/cores/c16/c16_mist.v
index 220d3ed..1e594cd 100644
--- a/cores/c16/c16_mist.v
+++ b/cores/c16/c16_mist.v
@@ -546,7 +546,7 @@ assign VGA_B  = ypbpr ? pb :  blue;
 // output is driven from the sync signals generated by the scan doubler. In
 // 15khz mode the VS signal is used as the RGB detect signal on the SCART 
 // connector and thus needs to be driven to 1
-assign VGA_HS = tv15khz?c16_cs:ypbpr ? (video_hs ^ video_vs) : video_hs;
+assign VGA_HS = tv15khz ? c16_cs:(ypbpr ? ~(video_hs ^ video_vs) : video_hs);
 assign VGA_VS = (tv15khz || ypbpr)?1'b1:video_vs;
 
 wire video_hs, video_vs;