diff --git a/plot.c b/plot.c
index 72fd4f0..c5888e0 100644
--- a/plot.c
+++ b/plot.c
@@ -2057,8 +2057,8 @@ static void cell_draw_marker_info(int x0, int y0)
 //      buf[k++] = 0;
       ili9341_set_background(DEFAULT_BG_COLOR);
       uint16_t color;
-      if ((setting.mode == M_LOW && temppeakLevel - get_attenuation() - setting.offset > -1) ||
-          (setting.mode == M_HIGH && temppeakLevel - get_attenuation()- setting.offset > -10))
+      if ((setting.mode == M_LOW && temppeakLevel - get_attenuation() + setting.offset > -1) ||
+          (setting.mode == M_HIGH && temppeakLevel - get_attenuation()+ setting.offset > -10))
         color = BRIGHT_COLOR_RED;
       else
         color = marker_color(markers[i].mtype);