diff --git a/modeline2edid b/modeline2edid
index 65142fd..da623e3 100755
--- a/modeline2edid
+++ b/modeline2edid
@@ -48,8 +48,8 @@ template-S() {
 	local arg
 	for arg in "$@"; do
 		case "${(L)arg}" in
-			[-+]hsync) [[ "${arg:1:1}" == "-" ]] || hsync_polarity=1 ;;
-			[-+]vsync) [[ "${arg:1:1}" == "-" ]] || vsync_polarity=1 ;;
+			[-+]hsync) [[ "${arg:0:1}" == "-" ]] || hsync_polarity=1 ;;
+			[-+]vsync) [[ "${arg:0:1}" == "-" ]] || vsync_polarity=1 ;;
 			ratio=*|xy_ratio=*) ratio="${arg#*=}" ;;
 			dpi=*) dpi="${arg#*=}" ;;
 			edid_version=*) edid_version="${arg#*=}" ;;