diff --git a/nanovna.h b/nanovna.h
index dc36f25..1ef3ede 100644
--- a/nanovna.h
+++ b/nanovna.h
@@ -287,7 +287,7 @@ extern int16_t lastsaveid;
 extern properties_t *active_props;
 extern properties_t current_props;
 
-extern uint8_t previous_marker;
+extern int8_t previous_marker;
 
 #define frequency0 current_props._frequency0
 #define frequency1 current_props._frequency1
diff --git a/plot.c b/plot.c
index c5b21f4..afc42eb 100644
--- a/plot.c
+++ b/plot.c
@@ -1291,7 +1291,7 @@ cell_draw_marker_info(int m, int n, int w, int h)
   cell_drawstring_5x7(w, h, buf, xpos, ypos, 0xffff);
 
   // draw marker delta
-  if (active_marker != previous_marker && markers[previous_marker].enabled) {
+  if (previous_marker >= 0 && active_marker != previous_marker && markers[previous_marker].enabled) {
     int idx0 = markers[previous_marker].index;
     xpos = 192;
     xpos -= m * CELLWIDTH -CELLOFFSETX;
diff --git a/ui.c b/ui.c
index 79d3da2..5789ff6 100644
--- a/ui.c
+++ b/ui.c
@@ -61,7 +61,7 @@ static int8_t inhibit_until_release = FALSE;
 enum { OP_NONE = 0, OP_LEVER, OP_TOUCH };
 uint8_t operation_requested = OP_NONE;
 
-uint8_t previous_marker = 0;
+int8_t previous_marker = -1;
 
 enum {
   UI_NORMAL, UI_MENU, UI_NUMERIC, UI_KEYPAD
@@ -673,21 +673,19 @@ menu_marker_op_cb(int item)
 static void
 menu_marker_sel_cb(int item)
 {
-  if (item >= 4)
-    return;
   if (item >= 0 && item < 4) {
-    if (markers[item].enabled) {
-      markers[item].enabled = FALSE;
-      if (item == active_marker) {
-        active_marker = previous_marker;
-        previous_marker = 0;
-      }
-      //choose_active_marker();
-    } else {
-      markers[item].enabled = TRUE;
+    // enable specified marker
+    markers[item].enabled = TRUE;
+    if (previous_marker != active_marker)
       previous_marker = active_marker;
-      active_marker = item;
-    }
+    active_marker = item;
+  } else if (item == 4) { /* all off */
+      markers[0].enabled = FALSE;
+      markers[1].enabled = FALSE;
+      markers[2].enabled = FALSE;
+      markers[3].enabled = FALSE;
+      previous_marker = -1;
+      active_marker = -1;      
   }
   if (active_marker >= 0)
     redraw_marker(active_marker, TRUE);
@@ -795,6 +793,7 @@ const menuitem_t menu_marker_sel[] = {
   { MT_CALLBACK, "MARKER 2", menu_marker_sel_cb },
   { MT_CALLBACK, "MARKER 3", menu_marker_sel_cb },
   { MT_CALLBACK, "MARKER 4", menu_marker_sel_cb },
+  { MT_CALLBACK, "ALL OFF", menu_marker_sel_cb },
   { MT_CANCEL, S_LARROW" BACK", NULL },
   { MT_NONE, NULL, NULL } // sentinel
 };