diff --git a/captcha/captcha.sh b/captcha/captcha.sh
index 0478b41..5e2fd3b 100755
--- a/captcha/captcha.sh
+++ b/captcha/captcha.sh
@@ -98,7 +98,7 @@ convert -size 180x60 xc:none -pointsize 40 \
 	-strokewidth 1 -draw \
 	"line $B2_LINE_START_X,$B2_LINE_START_Y $B2_LINE_STOP_X,$B2_LINE_STOP_Y" \
 	-wave "$WAVE2_AMPLITUDE"x"$WAVE2_LENGTH" \) \
-	\( -clone 0 -stroke white \
+	\( -clone 0 -stroke black \
 	-strokewidth 2 -draw "line 0,$W1_LINE_START_Y 140,$W1_LINE_STOP_Y" \
 	-strokewidth 2 -draw "line 0,$W2_LINE_START_Y 140,$W2_LINE_STOP_Y" \
 	-strokewidth 2 -draw "line 0,$W3_LINE_START_Y 140,$W3_LINE_STOP_Y" \
diff --git a/captcha/experimental.sh b/captcha/experimental.sh
index 0478b41..5e2fd3b 100755
--- a/captcha/experimental.sh
+++ b/captcha/experimental.sh
@@ -98,7 +98,7 @@ convert -size 180x60 xc:none -pointsize 40 \
 	-strokewidth 1 -draw \
 	"line $B2_LINE_START_X,$B2_LINE_START_Y $B2_LINE_STOP_X,$B2_LINE_STOP_Y" \
 	-wave "$WAVE2_AMPLITUDE"x"$WAVE2_LENGTH" \) \
-	\( -clone 0 -stroke white \
+	\( -clone 0 -stroke black \
 	-strokewidth 2 -draw "line 0,$W1_LINE_START_Y 140,$W1_LINE_STOP_Y" \
 	-strokewidth 2 -draw "line 0,$W2_LINE_START_Y 140,$W2_LINE_STOP_Y" \
 	-strokewidth 2 -draw "line 0,$W3_LINE_START_Y 140,$W3_LINE_STOP_Y" \