diff --git a/package-lock.json b/package-lock.json
index 930c16ca..f6c5ca40 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -17,7 +17,7 @@
         "leaflet-contextmenu": "^1.4.0",
         "leaflet-editable": "^1.2.0",
         "leaflet-editinosm": "0.2.3",
-        "leaflet-formbuilder": "0.2.6",
+        "leaflet-formbuilder": "0.2.7",
         "leaflet-fullscreen": "1.0.2",
         "leaflet-hash": "0.2.1",
         "leaflet-i18n": "0.3.3",
@@ -1377,9 +1377,9 @@
       "integrity": "sha1-8HFmTEpSe3b3uPm87HRLJIiVwHE="
     },
     "node_modules/leaflet-formbuilder": {
-      "version": "0.2.6",
-      "resolved": "https://registry.npmjs.org/leaflet-formbuilder/-/leaflet-formbuilder-0.2.6.tgz",
-      "integrity": "sha512-aBpR0PqvsFYVjPSwhPyOQGymQAmepOrZSXniwYimRSJMX7IO4TNeNv1Svwn7yiuKms7T0Y/Ib7KWnGy1c+A91Q=="
+      "version": "0.2.7",
+      "resolved": "https://registry.npmjs.org/leaflet-formbuilder/-/leaflet-formbuilder-0.2.7.tgz",
+      "integrity": "sha512-5/QXEPmlSPNzl5r8rNlhcQOfI2Bx9vo/FBaBCV7o37MmZZ2jyA4aRu+6j91CnyRmKXfU5f/42E0yJva/Dwnqcw=="
     },
     "node_modules/leaflet-fullscreen": {
       "version": "1.0.2",
@@ -3564,9 +3564,9 @@
       "integrity": "sha1-8HFmTEpSe3b3uPm87HRLJIiVwHE="
     },
     "leaflet-formbuilder": {
-      "version": "0.2.6",
-      "resolved": "https://registry.npmjs.org/leaflet-formbuilder/-/leaflet-formbuilder-0.2.6.tgz",
-      "integrity": "sha512-aBpR0PqvsFYVjPSwhPyOQGymQAmepOrZSXniwYimRSJMX7IO4TNeNv1Svwn7yiuKms7T0Y/Ib7KWnGy1c+A91Q=="
+      "version": "0.2.7",
+      "resolved": "https://registry.npmjs.org/leaflet-formbuilder/-/leaflet-formbuilder-0.2.7.tgz",
+      "integrity": "sha512-5/QXEPmlSPNzl5r8rNlhcQOfI2Bx9vo/FBaBCV7o37MmZZ2jyA4aRu+6j91CnyRmKXfU5f/42E0yJva/Dwnqcw=="
     },
     "leaflet-fullscreen": {
       "version": "1.0.2",
diff --git a/package.json b/package.json
index e6dcd033..b2995e06 100644
--- a/package.json
+++ b/package.json
@@ -41,7 +41,7 @@
     "leaflet-contextmenu": "^1.4.0",
     "leaflet-editable": "^1.2.0",
     "leaflet-editinosm": "0.2.3",
-    "leaflet-formbuilder": "0.2.6",
+    "leaflet-formbuilder": "0.2.7",
     "leaflet-fullscreen": "1.0.2",
     "leaflet-hash": "0.2.1",
     "leaflet-i18n": "0.3.3",
diff --git a/umap/static/umap/base.css b/umap/static/umap/base.css
index 05af31bf..5bc48647 100644
--- a/umap/static/umap/base.css
+++ b/umap/static/umap/base.css
@@ -669,6 +669,11 @@ input[type=hidden].blur + .button {
     /*box-shadow: inset 0 0 0 1px #215d9c;*/
     color: #efefef;
 }
+input:invalid {
+    border-color: red;
+    background-color: darkred;
+}
+
 
 /* *********** */
 /*   Alerts    */
diff --git a/umap/static/umap/js/umap.js b/umap/static/umap/js/umap.js
index 784b0f3c..3b85c2ac 100644
--- a/umap/static/umap/js/umap.js
+++ b/umap/static/umap/js/umap.js
@@ -14,6 +14,7 @@ L.Map.mergeOptions({
   default_popupContentTemplate: '# {name}\n{description}',
   default_interactive: true,
   default_labelDirection: 'auto',
+  maxZoomLimit: 20,
   attributionControl: false,
   editMode: 'advanced',
   embedControl: true,
@@ -1502,15 +1503,26 @@ L.U.Map.include({
           handler: 'BlurInput',
           helpText: `${L._('Supported scheme')}: http://{s}.domain.com/{z}/{x}/{y}.png`,
           placeholder: 'url',
+          type: 'url',
         },
       ],
       [
         'options.tilelayer.maxZoom',
-        { handler: 'BlurIntInput', placeholder: L._('max zoom') },
+        {
+          handler: 'BlurIntInput',
+          placeholder: L._('max zoom'),
+          min: 0,
+          max: this.options.maxZoomLimit,
+        },
       ],
       [
         'options.tilelayer.minZoom',
-        { handler: 'BlurIntInput', placeholder: L._('min zoom') },
+        {
+          handler: 'BlurIntInput',
+          placeholder: L._('min zoom'),
+          min: 0,
+          max: this.options.maxZoomLimit,
+        },
       ],
       [
         'options.tilelayer.attribution',
@@ -1541,15 +1553,26 @@ L.U.Map.include({
           helpText: `${L._('Supported scheme')}: http://{s}.domain.com/{z}/{x}/{y}.png`,
           placeholder: 'url',
           helpText: L._('Background overlay url'),
+          type: 'url',
         },
       ],
       [
         'options.overlay.maxZoom',
-        { handler: 'BlurIntInput', placeholder: L._('max zoom') },
+        {
+          handler: 'BlurIntInput',
+          placeholder: L._('max zoom'),
+          min: 0,
+          max: this.options.maxZoomLimit,
+        },
       ],
       [
         'options.overlay.minZoom',
-        { handler: 'BlurIntInput', placeholder: L._('min zoom') },
+        {
+          handler: 'BlurIntInput',
+          placeholder: L._('min zoom'),
+          min: 0,
+          max: this.options.maxZoomLimit,
+        },
       ],
       [
         'options.overlay.attribution',