diff --git a/config.js b/config.js
index a3c14dd..0568315 100644
--- a/config.js
+++ b/config.js
@@ -67,4 +67,7 @@
         //'Mapsforge Tile Server': 'http://localhost:6090/{z}/{x}/{y}.png'
     };
 
+    // Minimum transparency slider value on load, values between 0 and 1 (0=invisible).
+    // 0 = no minimum, use stored setting; 1 = always reset to full visibility on load
+    BR.conf.minOpacity = 0.3;
 })();
diff --git a/js/control/OpacitySlider.js b/js/control/OpacitySlider.js
index 38ec888..3123789 100644
--- a/js/control/OpacitySlider.js
+++ b/js/control/OpacitySlider.js
@@ -8,7 +8,12 @@ BR.OpacitySlider = L.Control.extend({
         var container = L.DomUtil.create('div', 'leaflet-bar control-slider'),
             input = $('<input id="slider" type="text"/>'),
             item = localStorage.opacitySliderValue,
-            value = item ? parseInt(item) : 100;
+            value = item ? parseInt(item) : 100,
+            minOpacity = (BR.conf.minOpacity || 0) * 100;
+
+        if (value < minOpacity) {
+            value = minOpacity;
+        }
 
         var stopClickAfterSlide = function(evt) {
             L.DomEvent.stop(evt);